Rick's Free Auto Repair Advice » Trailblazer

ABS light on GM vehicles

Rick — Fri, 16 Apr 2010 17:17:57 +0000

GM has issued a TSB #04-05-025-002A covering the following vehicles:
2004 Buick Rainier
2002-04 Cadillac Escalade, Escalade EXT
2003-04 Chevrolet Silverado
2000-04 Chevrolet Suburban, Tahoe
2003-04 Chevrolet Avalanche, Trailblazer
2003-04 Chevrolet SSR
1999-04 GMC Sierra
2000-04 GMC Yukon, Yukon Denali, Yukon XL
2002-04 GMC Envoy
2004 GMC Envoy XUV
2002-2004 Oldsmobile Bravada

The problem shows up as a glowing ABS light and trouble coded C0265, C0201, U1041 and a loss of communication with the brake module (EBCM). The TSB warns dealers NOT to replace the EBCM. The problem is a bad ground. Refer to a wiring diagram to find the grounding location for your vehicle. Then clean the ground area and spray it with rubberized undercoating.

For midsized utility vehicles, find the location of ground #304
For Chevrolet SSR, find the location for ground #400
For full-size trucks and utilities, find the location for ground #110

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Key won’t come out of ignition switch – GM vehicles

Rick — Fri, 26 Mar 2010 23:44:23 +0000

Believe it or not, this is related to a rash of bad ignition switches in GM vehicles. When the switch fails in the open position, it doesn’t provide battery power to the Brake Transmission Shift Interlock (BTSI) fuse. The BTSI system consists of the brake pedal switch and a solenoid on the shifting mechanism. The BTSI prevents you from shifting into and out of park unless your foot is pressing on the brake pedal. Unfortunately, when the ignition switch fails, the BTSI system also prevents you from completely shifting into park and removing the key.

To confirm that this is the cause of the problem, check for battery voltage at the BTSI fuse in the fuse box with the ignition turned OFF. If you don’t get voltage at the fuse, move to the ignition switch. Check for battery voltage at the B+ terminal. It should read within 1 volt of battery voltage. If not, replace the ignition switch

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No instrument panel, HVAC controls dead, blower motor dead, flashers dead, GM vehicles

Rick — Sun, 21 Mar 2010 07:36:08 +0000

Bad ground TSB for GM vehicles

GM has issued a TSB #04-08-45-010 covering 2004-05 Buick Rainier, 2002-05 Chevrolet Trailblazer, 2002-05 GMC Envoy, and 2002-03 Oldsmobile Bravada.

The bad ground connection can cause the instrument panel lights to be inoperative, HVAC controls inoperative, blower motor inoperative, radio inoperative, flashers inoperative, and transfer case controls inoperative. The cause has been found to be a poor ground at a splice area G201 located on the right side of the front console area.

To fix the problem, you must remove the center floor console. Then remove the 4 screws that hold the instrument panel lower closeout carpet panel to the instrument panel. Next, remove the panel.

Remove the splice pack bolt. If the bolt is corroded, clean it with a wire brush. Remove any carpet that was trapped during assembly. Clean the ground surface with emery cloth. Reassemble the panel and console.

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ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

Performance Chip? GM Revokes Warranty on Chipped Vehicles

Rick — Fri, 18 Dec 2009 23:16:46 +0000

GM issued a technical service bulleting (TSB) #09-06-04—026 regarding revocation of warranty coverage on any GM vehicle in which the factory calibrations (software) has been removed or altered. The TSB applies to ALL GM gasoline passenger cars and trucks from 2006- present.

It’s important to note that GM is seeing enough damaged engines and transmissions to make this announcement. Here’s a direct quote from the TSB:

“When alteration to the GM-released engine or transmission control calibrations occurs, it subjects powertrain and driveline components (engine , transmission, transfer case, driveshaft and rear axle) to stresses that were not tested by General Motors. It is because of these unknown stresses, and the potential to alter reliability, durability and emissions performance, that GM has adopted a policy to cancel any remaining warranty coverage to the powertrain and driveline components whenever the presence of a non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is subsequently removed.”

The TSB goes on to instruct the dealers on how to determine if the factory calibrations have been altered or removed. So don't think you change restore the factory programming and tear into the dealer when they refuse to cover your warranty claim. They CAN tell what you've done.

So, if you’re planning on “chipping” your vehicle (which I do NOT recommend), be aware that you’re on your own and that the likelihood of damage to the engine and transmission increases dramatically.

Also, remember this: engine design is always a compromise between power, responsiveness, emissions, and fuel economy. You cannot change one variable without changing all the others. So, while chipping may increase power in one range of operation, you will pay for it in other areas. There’s no free lunch, despite what the chipmakers want you to believe.

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Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
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If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

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ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

Headlights flicker on vehicle with daytime running lights

Rick — Sun, 06 Dec 2009 18:02:10 +0000

Every manufacturer has their share of problems with daytime running lights. Basically the system senses that the vehicle is running and the headlight switch is off. Programmed conclusion? Must be daylight, otherwise the driver would turn on the headlights. Other systems have light sensors. The Chrysler Daytime Running Light system gets screwed up by corrosion in the intelligent power module. Some GM vehicles fail due to a cracked Daytime Running Light resistor (computer provides power to the headlights, but runs it through a resistor to cut down on the headlamp brightness). Still another GM system runs the headlight commands through Daytime Running Lamp Module located behind the left side of the instrument panel. This module contains a diode that has a high failure rate. The module sends a command to the Daytime Running Lamps Relay located in the convenience center (firewall passenger side).

If you have the latter system, remove the relay and insert a jumper wire across the power terminals. See Relay Layout. If that fixes the problem, replace the relay. If it doesn’t, replace the Daytime Running Lamp Module.

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Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
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If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

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ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

Key stuck in ignition, GM vehicles

Rick — Mon, 12 Oct 2009 18:59:15 +0000

GM has issued a TSB #05-07-30-021B regarding stuck ignition keys. The TSB applies to 2004-07 Buick Ranier, 2002-08 Chevrolet Trailblazer,, 2002-08 GMC Envoy, and 2003-04 Oldsmobile Bravada.

The most common cause of the problem is the shifter boot caught in the shifter mechanism. Start by inspecting the shifter boot to see if it is caught in the shifter assembly. If it is, reposition the shifter boot. If the boot is damaged, replace it with a new shifter boot. GM warns NOT to replace the entire shifter mechanism. The problem is only with the boot.

Alldatadiy.com

eautorepair.net

Both Alldata and Eautorepair offer professional grade shop manuals at a price you can afford. Check them out!.

Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
Click on REPAIR TOPICS to read individual articles written for specific automotive systems

If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

Click on the link below for speedy navigation:

ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

Anti-Theft Systems for GM Vehicles

Rick — Fri, 29 May 2009 16:33:00 +0000

GM has used a variety of anti-theft systems on their vehicles. When you get a no start, intermittent start, or start then die, you should diagnose the anti-theft system before you start replacing starting components. A tell-tale sign that you’ve got an anti-theft problem is a flashing “Theft” light. Here’s a brief primer on each system and what to look for.

Each GM anti-theft system disables different components. Some disable the engine starter, while others enable the starter but disable fuel injectors. None of them disable spark. So, first understand the difference between vehicle theft deterrent systems.

VAT
The VAT, or vehicle anti-theft was used primarily on 1986-88 Corvettes. The key had a pellet that was married to the vehicle anti-theft module at the factory. If the lock cylinder was turned or bypassed with the proper key installed, the system would disable the starter and kill the injectors. You could NOT perform a system “relearn.”

PassKey I, and II
Similar to the VATS system, these vehicles also used a pellet key. You can identify this system by looking at the key. It has a black resistor pellet with a thin metal edge running along the key. The system enables the starter, but shuts down the injectors after initial startup. So the vehicle would start, then die. This system has a “relearn” feature. It was used on these vehicles

Buick
Century 97-01
Park Avenue 91-96
LeSabre 92-99
Riviera/Reatta 90-01
Regal 94-99
Roadmaster 94-96

Cadillac
Eldorado 89-01
Seville 89-97
Fleetwood 92-96
Deville 90-99
Allante 89-93

Chevrolet
Camero 89-01
Corvette 89-01
Caprice/Impala 94-96
Lumina/Monte Carlo 95-97

Oldsmobile
Cutlass Supreme 94-97
Aurora 95-00
Regency/88 91-99
Toronado 90-93
Pontiac
Firebird 89-01
Grand Prix 94-96
Bonneville 92-99

PassKey III
This system uses a special key (PK3 stamped on the shoulder of the key) with a transponder under the rubber cover. The receiver module is located next to the lock cylinder. When the key is positioned next to the lock cylinder receiver module, it energizes the transponder which sends a coded signal to the receiver. The receiver module checks its memory to see if the signal is correct. If it is, the module sends a signal to the PCM to enable the engine. If the value is valid, the indicator light will remain steady for 2 seconds. You cannot test this system with an ohmmeter. You need a scan tool. If the signal is not correct, the PCM disables the injector and the starter and flashes the light once per second. If an illegitimate key is used or a system problem exists, the light flashes twice per second.

The system is used on:

Buick
Lesabre 2000-on
Park Avenue 97-on

Cadillac
Seville 98-on
Deville 2000-on

Oldsmobile
Aurora 01-on

Pontiac
Bonneville 2000-on

GM Minivans
Venture, Montana, Silhouette

Passlock
This system allows starter operation, then kills the injectors 1-2 seconds after startup. This is a “Hall-Effect” system. The key cylinder housing has a small magnet that rotates past the Passlock sensor. The sensor is powered and detects the rotation. The voltage on the sensor then drops to a specified value (there are 10 different values). There’s no pellet in the key. So basically this system is checking to see that a thief has not popped the lock cylinder to steal the vehicle. you have to perform a Powertrain Control Module (PCM) relearn procedure (need a programming scan tool). The Passlock system was used on:

Buick
Skylark 96-98

Chevrolet
Cavalier 95-on
Impala 2000-on
Malibu 97-on
Monte Carlo 2000-on

Oldsmobile
Achieva 96-on
Cutlass 97-on
Intrigue 98-on

All GM trucks 98-0n

SYSTEM DIAGNOSTICS

PassKey I and II System Diagnostics

There are 15 different key codes. Measure the resistance of the key pellet by connecting an ohmmeter to each side of the key pellet. Once you find the resistance value, remove the lower dash panels and locate two small wires (both white) that run down the base of the steering column. Disconnect the electrical connector where those wires terminate. Then connect an ohmmeter to that electrical connector and insert the key. The reading you get at the end of the two white wires should match the resistance value you got from the key. Next, turn the key. The value on your meter should NOT change or drop out. If it does, you will have to replace the key cylinder. It is COMMON for the wires to break from the key cylinder.

If you have the PassKey system and the engine cranks, runs, and quits AND the THEFT light is on (for about 5 seconds), here are the tests you should perform:

1) Disconnect the electrical connector at the deterrent module. Then turn the ignition switch to RUN while you test the voltage between the dark blue wire in the theft deterrent electrical connector (the one you just disconnected) and a ground point. You should see 5 volts. If you don't get that voltage, check for an open or short between the dark blue wire and the PCM that supplies the voltage to the module.

If you DO get the 5 volts, turn the ignition off and reconnect the electrical connector. Pierce the insulation on the same wire (with a pin) or back-probe the wire in the connector. Turn the ignition to RUN. The voltage should now read 2.5 volts. If not, replace the theft module. THAT assumes you have already conducted the key pellet test (explained above) and that it passes the test. If you see 2.5 volts and the vehicle still won't stay running, check the fuel pump relay.

Here's how it works, The lock cylinder reads the resistance of the pellet in the key and transmits that data to the theft module. Meanwhile, the PCM provides 5 volts on the dark blue wire. When the theft module determines that the proper key has been inserted, it partially grounds the voltage on the dark blue wire. The PCM initially provides fuel injector pulse, but if it doesn't sees a voltage drop on that dark blue wire, it cuts off the fuel injectors. That's why you get a crank, start, engine shut down.

So, if the vehicle starts and then dies, AND THE THEFT LIGHT FLASHES, the module is not getting the proper signal from the lock cylinder or the module is bad.

Passlock
Testing this system is similar to the Passkey I and II systems. You want to check the voltage at the bottom of the steering column as you insert the key and rotate it check the yellow signal wire (should be 5 volts before you start the testing). Turn the key.

The value should drop. If it does not, you will have to replace the key cylinder. The “control module” for this system is built into the instrument panel control (IPC) in early years. In later years, the system is controlled by the Body Control Module (BCM), the Electronically Controlled Orifice-steering Assist (EVO), IPC and other systems. If you have to replace the lock cylinder or any of the control modules,

Passkey III

You cannot check this system with an ohmmeter. You will need a scan tool to watch the operation of the system and find the trouble code. Once you get the trouble code, follow the diagnostic procedure based on the specific code.

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eautorepair.net

Both Alldata and Eautorepair offer professional grade shop manuals at a price you can afford. Check them out!.

Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
Click on REPAIR TOPICS to read individual articles written for specific automotive systems

If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

Click on the link below for speedy navigation:

ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

ABS Code C0040—GM and Saab Vehicles

Rick — Wed, 12 Nov 2008 02:20:00 +0000

GM has issued a technical service bulletin for Buick Rainier (05-07), Chevrolet TrailBlazer (05-08), GMC Envoy (05-08), and Saab 9-7X. The TSB #07-05-25-006 relates to a problem with the ABS system and results in a scan code C0040. GM advises you to inspect the right front wheel speed sensor for damage caused by rubbing against the A/C pulley. If you find damage, wire in a splice and then reroute the wires away from the pulley.

Alldatadiy.com

eautorepair.net

Both Alldata and Eautorepair offer professional grade shop manuals at a price you can afford. Check them out!.

Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
Click on REPAIR TOPICS to read individual articles written for specific automotive systems

If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

Click on the link below for speedy navigation:

ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

GM Passlock–Diagnosing and Fixing GM Anti-theft related no-starts

Rick — Tue, 13 May 2008 03:11:00 +0000

The GM Passlock system is fairly simple, especially when compared to other makes. However, if yours is goofing up, you won’t think it’s so simple.

Here’s how it works: When you first turn the key, the PCM provides power to the fuel pump, injectors, and ignition system. You can crank and start the engine. However, there’s a magnet built into the lock cylinder. As you rotate the key, the magnet passes over a Hall Effect sensor—a sensor that detects the presence of a magnetic force. The magnet produces a unique voltage when it passes over the sensor. The sensor sends this voltage signal to the Body Control Module where it is compared to a stored value. If the sent voltage doesn’t match the stored value, the PCM shuts down the fuel injectors for a minimum of 10 minutes and, well, you’re pretty screwed at that point. If you try to start the car again, you will see a blinking Security light. That’s your sign that the Passlock system has shut you down.

What goes wrong: GM vehicles experience a very high failure rate in the lock cylinder and lock housing mechanisms. Fortunately, they’re fairly inexpensive and easy to replace.

Testing the Passlock sytem: Remove the plastic cover shrouds from the steering column near the lock cylinder. Inside you will see the Passkey module surrounding the lock cylinder. It will have 3 wires coming out of it. Turn the key to the ON position and use a DIGITAL multimeter (Do NOT use an analog meter) to backprobe the probe the black and white wires. If you see 12 volts on the white wire and 0 volts on the black wire, you can proceed to the test for the Passkey module. If you do not see those voltage values, you have a wiring problem between the connector and the BCM.

Next, connect your voltmeter to the yellow wire. It should read 5 volts. Keep the probe connected and turn the key to the off position and back to the start position. The Passlock Data Voltage has a potential of 10 different values, ranging from .86 to 4.28 volts. The voltage should drop to a voltage level between those values and stay within .02 volts of the initial reading for at least one minute. Repeat the test several times—you must receive the same voltage for each test. If you do not, replace the lock cylinder and the Passkey housing.

To remove the lock cylinder, first disconnect the negative battery cable and allow the airbag to power down for 5-10 minutes. Slide the Passkey module off the cylinder housing. Insert the key and turn the lock cylinder to the start position. Place a 1/16” allen wrench into the hole on top of the lock module to release the steering column lock cylinder set pin. Then turn the lock cylinder to the RUN position and pull the lock cylinder out. Reverse the procedure to install.

After you replace the cylinder and Passkey module, you will have to conduct a relearn procedure for the BCM to learn the new voltage value. Here’s the procedure: Lock doors and unlock. Clear codes. Turn key and bump starter, leave on for 10 minutes. After a few minutes the dash light will go out. At that point, turn the key to the off position for 90 seconds to 3 minutes. Repeat this procedure 3 times for a total of 30 minutes and on the 4th try the car will start.

Alldatadiy.com

eautorepair.net

Both Alldata and Eautorepair offer professional grade shop manuals at a price you can afford. Check them out!.

Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
Click on REPAIR TOPICS to read individual articles written for specific automotive systems

If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

Click on the link below for speedy navigation:

ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use

Engine flush

Firing order, cylinder layout, finding #1 cylinder

MAF or MAP sensor

Oxygen sensors, How they work, How to change, How to test

PassLock or Passkey

Thermostat issues

Transmission flush

Serpentine belt diagrams

Window issues, power window motor, replace window regulator, glass adhesive

Turn Signal Problems—GMC/Chevrolet Trucks

Rick — Thu, 01 May 2008 00:15:00 +0000

Some shops have been reporting repeat failures with the factory trailer adapter on GM trucks. The symptoms show up as all turn signal lights flashing when you turn left or right and constant power at the trailer harness. The adapter may also cause all other kinds of turn signal abnormalities. At first glance you may think to replace the turn signal switch assembly, but check the trailer adapter first. The adapter is located down by the spare tire and is either a black or aluminum colored box.

Start by checking the wiring connections. If they are good, unplug the connector to the adapter. If the problem disappears, replace the box. The problem is most likely a shorted diode inside the adapter.

Alldatadiy.com

eautorepair.net

Both Alldata and Eautorepair offer professional grade shop manuals at a price you can afford. Check them out!.

Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem

Click on MAKE an MODEL to see all the articles I've written for your vehicle
Click on REPAIR TOPICS to read individual articles written for specific automotive systems

If you've had your car scanned and know the trouble code go to TROUBLE CODES

Here are some quick links to speed up your research

Click on the link below for speedy navigation:

ABS issues, how to bleed ABS brakes

Airbag issues or SRS light on

Alternator issues or how to test

Belt diagram or serpentine belt issues

Blower motor

Blower motor resistor

Brakes, brake issues, what kind of brake parts to buy, ABS issues

Car Alarms or Antitheft systems

Cooling system, Water pump, What type of coolant to use