Rick's Free Auto Repair Advice » Chevrolet

Won’t shift out of park

Rick — Sat, 05 Nov 2011 19:23:52 +0000

Most vehicles now come with a shift interlock device to prevent you from shifting into or out of gear without having your foot on the brake pedal. The switch is built into the brake light switch and when it determines your foot is on the pedal, it energizes a shift interlock solenoid. The solenoid pulls a locking pin out of the way so you can shift. When the system fails, it’s either the brake light switch of the solenoid. In the past you’ve had to buy the solenoid from the dealer. Now Dorman makes an aftermarket solenoid to fit

Dorman 924-705

Want more more information on this repair or any others for your vehicle, buy an online subscription to either Alldatadiy.com or eautorepair.net. Click on this link to compare the two services: Compare Alldata and Eautorepair.

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Intermittent problems on GM vehicles

Rick — Thu, 08 Sep 2011 21:23:07 +0000

GM vehicles from the mid ’90′s to the present are known for faulty ignition switches. The problems are almost always intermittent. Intermittent starting, dying while driving, A/C to start blowing warm air or for the blower fan to stop (depending on which GM model we’re talking about), along with an ABS light. In fact, any time you see erratic or intermittent problems that could be electtrical in nature on a GM vehicle, you should immediately suspect the ignition switch. Always test the igntion switch during an intermittent problem to see if the switch is providing power (use a meter).Or, wiggle the wires going to the switch. GM techs replace so many of these that it’s almost automatic for them to head there first

In the case of the A/C the problem is usually the ignition switch heating up and not providing power to the A/C clutch and the ABS computer. If you want to diagnose the problem, buy a wiring diagram for your vehicle form eautorepair.net or alldata.com (there are way to many GM models to list their wiring diagrams here) and test for power at the switched terminals when the problem happens. Or, just replace the ignition switch.

For more information on this repair or any others for your vehicle, buy an online subscription to either Alldatadiy.com or eautorepair.net. Click on this link to compare the two services: Compare Alldata and Eautorepair.

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

P0332, Circuit Low Input (Bank 2) on GM products

Rick — Tue, 06 Sep 2011 04:10:36 +0000

Also P0335 and P0340

If you think you should replace the knock sensor after getting this code, think again. This is a perfect example of where a sensor can be telling the truth and the root cause of the problem is somewhere else. Here’s the scoop. Most late model engine use variable valve timing to change the opening and closing timing of the valves. The device that actually changes the valve timing is called the cam phaser (yeah, like on Star Treck). Some cam phasers use oil pressure to rotate the camshaft slightly to change the timing. That’s great when it’s working well. But if you’ve changed your own oil and used a viscosity that’s different from the manufacturer’s recommendations, you can screw up the phaser. For example, some people don’t believe the manufacturer’s recommendation to use 5W-30. So they change their oil with 10W-30. The slightly thicker oil can cause the phaser to respond more slowly to computer commands. And when the cam is out of phase from the commanded position, you can get pre-ignition, or pinging. Yup, if you used this oil and now have this trouble code, point your finger right at yourself.

The same holds true if you think you can get away with not changing your oil on time. Think sludge buildup isn’t a problem? Well guess what, sludge in a cam phaser can also cause trouble codes.

If you’re getting these codes and think it might be caused by oil, change your oil and filter and drive the vehicle first. Perhaps the clean oil can clear out the passages.

Here are a few other things that can cause this trouble code:

Check the electrical connector on the cam phaser. If you see oily buildup, disconnect the connector and check inside. Oil can sometimes seep into the connector and that would give false readings.

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A/C doesn’t work and ABS light on

Rick — Thu, 01 Sep 2011 17:53:39 +0000

GM vehicles are known for faulty ignition switches. The problems are almost always intermittent. One common symptom is for the A/C to start blowing warm air or for the blower fan to stop (depending on which GM model we’re talking about), along with an ABS light. The problem is usually the ignition switch heating up and not providing power to the A/C clutch and the ABS computer. If you want to diagnose the problem, buy a wiring diagram for your vehicle form eautorepair.net or alldata.com (there are way to many GM models to list their wiring diagrams here) and test for power at the switched terminals when the problem happens. Or, just replace the ignition switch.

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eautorepair.net

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

Rear Brakes – Uneven brake pad wear, noise, on vehicles with rear disk brakes

Rick — Sun, 28 Aug 2011 17:43:19 +0000

Rear disk brakes are exposed to the same road debris, salt, snow, rain, and heat as front brakes. But because they do only 20% of the braking, they don’t get worn as quickly. That leaves them especially vulnerable to the elements. Since the pads don’t wear as quickly, the caliper doesn’t slide on the caliper pins nearly as far, so caliper pin rusting is far more common. This is especially true in 2000-06 Chevrolet Silverado, Avalanche, and Suburban 1500 trucks.

Every time a caliper slides on the pins, air is either expelled or sucked in. Some manufacturers install a rubber cup over the air breathing hole to allow air to flow but keep out water and road debris. In the Chevrolet design, GM drilled pin holes in the bracket and covered them with rubber bushings. Unfortunately, those rubber bushing aren’t doing the job and the rear caliper pins are rusting and seizing in the bracket. When that happens, the caliper can’t slide and applies braking pressure to only the inboard pad. The result is uneven braking, noise, vibration, and loss of stopping power.

Even though this is a problem on GM trucks, it can happen to any vehicle. I’ve seen caliper pins so frozen in the bracket that the only option is to replace the entire mounting bracket. In fact, this is happening so often that rebuilders are now selling rebuilt brackets

Buy a rebuilt caliper bracket to correct rusted and seized caliper pins

so you don’t have to buy a complete caliper.

One way to avoid this problem is to service the rear calipers about once a year. Retract the rear caliper piston slightly with a special tool (see below). Then remove the caliper. Grease the slide pins with Permatex synthetic brake grease and reinsert the caliper pins. Also apply the grease to the abutment areas where the pads slide

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

A/C leak in Chevrolet Venture, Olds Silhouette, Pontiac Aztek, Pontiac Montana, and Buick Rendezvous

Rick — Wed, 24 Aug 2011 16:12:08 +0000

A/C leak in Chevrolet Venture, Olds Silhouette, Pontiac Aztek, Pontiac Montana, and Buick Rendezvous

Many owners of the 2001-02 GM minivans above are complaining of poor A/C operation. The cause is often a leak in the condenser (the finned unit in front of the conventional radiator). Due to poor design, the condenser cracks right near the lower right hand attaching bracket. The only solution is a new condenser (thanks GM). GM has issued a new improved part to solve future cracking problems. The part number is 10339103 (black), or 10339104 (unpainted). Replace the old unit with the new, but don’t install a bolt in the lower right attachment bracket—it stays blank.

Here’s an aftermarket version of the GM part

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Instrument Cluster Doesn’t Work

Rick — Mon, 08 Aug 2011 02:18:30 +0000

GM has issued a Technical Service Bulletin (1549143) for 2001-05 Chevrolet Silverado and GMC Sierras equipped with the Allison LCT1000 transmission. The instrument cluster can be erratic, drop out, become inoperative, or result in a trouble code of P0721, C0237, P0500, C0055. In addition, the transmission may exhibit trouble shifting. Also, the ABS light can illuminate. The problem may be caused by a bad vehicle speed sensor (VSS) or a damaged reluctor wheel.
The Allison tranmission sends a speed signal to the transmission control module. The signal is AC voltage of 34Hz at 1MPH. The transmission control module converts the AC signal to a digital waveform and sends it to the powertrain control module. That speed signal is then fed to the instrument cluster, radio, ABS brake module and the cruise control. So a bad VSS can be the source of all these problems. I could tell you how to test the sensor, but you’d need an expensive Fluke multimeter. It’s cheaper to replace the sensor.

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

GM vehicles with B0071 or B0081 trouble codes.

Rick — Mon, 18 Jul 2011 02:02:52 +0000

If you own one of the vehicles listed below and see a lit SRS (supplemental restraint system) light on your dash, you may have one or both of these trouble codes: B0071 or B0081. Both codes relate to a problem in the Sensing and Diagnostics module. Don’t start replacing air bad components like the clock spring or the module. The problem is most likely the result of a defective seat belt tensioner sensor located in the passenger side seat belt buckle. Contact the dealer for the updated sensor and install it. That should clear the code.

2005-07 Buick Terrazas
2005-09 Chevrolet Uplander, Pontiac Montana
2006-07 Chevrolet Impala
2006-10 Buick Lucerne, Cadillac DTS, Chevrolet HHR, Hummer H3s
2207-10 Cadillac Escalade, ESZ and EXT, Chevrolet Avalanche, Cobalt, Silverado, Suburban, Tahoe, GMC Canyon, Sierra, Yukon, Yukon Denali, Yukon XL, Pontiac G5
2009-10 Hummer H3Ts

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Saturn, Chevrolet Cobalt, Pontiac Pursuit, Oil Leak

Rick — Fri, 03 Jun 2011 16:54:57 +0000

GM has issued a TSB (TSB 06-06-01-013) Customers are reporting an oil leak coming from the rear of the engine on 2006 Saturn ION and VUE, Chevrolet Cobalt, Pontiac Pursuit models with the 2.2-liter Ecotec Four engine. The leak looks like it’s coming from the rear main seal, but it’s usually not. Instead, look at the oil galley plugs just above the rear main seal. The plugs may have been damaged or improperly torqued during engine assembly.
To confirm the leak, you’ll have to remove the transmission and flywheel. If the oil is coming from the plugs, remove them and check the threads. If they look ok, apply sealant (#12346004) and re-install them to 44-ft-lbs. However, if the threads are stripped, replace them with new plugs, apply sealant and re-torque.

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Electronic Fan Clutch Failures on Rainier, Trailblazer, S10, Isuzu Ascender, Oldmobile Bravada, Saab 9-7X, and S15 GMC Envoy

Rick — Tue, 15 Mar 2011 05:16:03 +0000

Electronic Fan Clutch Failures on Rainier, Trailblazer, S10, Isuzu Ascender, Oldmobile Bravada, Saab 9-7X, and S15 GMC Envoy

The electronic fan clutch in the above vehicles experiences almost a 100% failure rate. The purpose of the fan is to reduce drag on the engine at highway speeds where “ram-air” is enough to cool the radiator. At highway speeds, a fully engaged clutch actually spins slower than the air coming through the radiator. So it reduces gas mileage. Thermostatically controlled viscous fan clutches have been around for decades to solve the problem. Those clutches are made from two halves with concentric circles that mesh. The gaps are filled with a silicone fluid. As the engine temperature rises, a thermostatically controlled valve closes off the flow of fluid and the concentric circles lock together under the pressure, transmitting the full torque to the fan blade. However, at higher speeds, the rush of aid past the thermostatic coil opens the valve, allowing the circles to disengage. At that point the fan blade “free-wheels” with the ram air.
Starting in 2002 GM replace the thermostatic coil with an electronically controlled “duty cycle” solenoid and an RPM indicator. The powertrain control module monitors engine and road speed and calculates how fast the fast should turn to properly cool the engine. To adjust fluid pressure in the clutch, the PCM pulses the solenoid on and off in short burst. This is called “duty-cycle.” For example, GM may divide each second into to pulses. If the PCM commands the solenoid on five times every other 1/10 of a second, the fan has a 50% duty cycle. The see how well things are working, the PCM compares the actual fan RPM to the RPM it expected when it calculated duty cycle. If the two speeds don’t match, the PCM makes further adjustments.
When the electronic fan clutches fail, they can lock on full time or free-wheel full time. Free-wheeling causes overheating and lock up reduces gas mileage and causes a howling noise at highway speeds.
To replace the fan clutch you’ll have to remove the fan shroud and fan blade. Mark the orientation of the fan blade before unbolting it completely. It must go back on in the same way. Then unbolt the old electronic fan clutch and swap it out.
The list price on a new fan clutch from the dealer is around $234. But Dorman Products makes an aftermarket replacement for $130. This is a new (not rebuilt part).

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eautorepair.net

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