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Sedans Pontiac Bonneville Pontiac Bonneville General Maintenance and Repair
2228 messages, Last post on Nov 29, 2009 at 4:40 PM
You are in the Pontiac Bonneville Forum. Your Hosts are pat & karens
Interesting to hear about the voltage drop problem. We were never told this--no mention of a service bulletin at our trusty Pontiac dealer. We had this problem appear in 1999, the dealer replaced the instrument cluster. When the vehicle was returned to us, the A/C was inoperative, which was repaired with a new evaporator coil. hen, when the vehicle was returned to us the A/C still did not work>bad solenoid. So that was a $ 2000 repair. A year later, same problem with the voltage drop. We just had a new battery the prior winter, so the repair shop put in a new alternator (rebuilt $ 400.) By the way, the A/C also went bad a year later and we had the entire system replaced with the new refrigerant type. So far, spent about $4500 in repairs in the last 3 years. I'm seeking a new vehicle-since the repairs are costing me as much as a payment lately. I now avoid the dealer at all costs--they have been unable to make competent repairs that fixed the problem. Too bad since the vehicle has only 60,000 miles on it and looks like new.
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| Could be a number of issues, however, I just got rid of my '92 and it had the same problem. A new switch in the door fixed it, and it was relatively inexpensive and easy to replace. However, the problem still persisted at times, for reasons I am not sure of. Sometimes it works, sometimes it did not. The switch is a cheap fix, and the solenoid is obviosly working and you do have power to it as it works when you use the key fob. To replace the switch you may destroy the old one in the process, but so what. The new switch construction should be self explanitory as to how the old one is hanging on, and you should not have to remove the door panel. | |
| What ABS codes were retrieved? Without that information it's impossible to make an accurate diagnosis or suggest an appropriate repair strategy. "It needs a pressure module valve assembly" is too vague. Btw, that's "pressure modulator". There are about 16 trouble codes relating to the pressure modulator. Some are fixable, some aren't. | |
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Thanks for the response. In looking at the printout from the dealer, I see no codes. "Tested system and found failure in pressure module (as spelled by the printout, modulator sounds correct to me) valve and right front hub and bearing assembly." To the tune of $ 1,300.00 What I know is the computer command ride option also lights both ride types and I understand may be related. The ABS/traction control lights are not on all the time, but come on quite quickly after driving. The system activates in ABS mode when the system lights are off while parking the car, say backing into a parallel spot, going 2 mph.(you can feel it in the pedal and hear the "growl") It will then activate in traction control mode when "taking off", even if taking off consists of lightly touching the accelerator to adjust that same parking position. Obviously way over sensitive like my first wife. This is not a real issue as the lights seem to come on rather quickly after driving a short distance, and the system seems inoperable at that time. I am suspect of certain parts of the diagnosis. I had the Pontiac dealer do a diagnostic check for a number of issues, as I was buying the car used from a Chevy dealer down the street. I wanted the ABS issue checked by a Pontiac dealer due to different electronics than Chevrolet. The Pontiac dealer that did the diagnostics found noise in the Supercharger among other things (I hear no unreasonable or obvious noise)and although this may be true, I don't think it needs $700 dollars worth of supercharger work. I wonder about the spindle and bearing assembly and will check that thouroughly myself, however, I do wonder if this could be causing my ABS issues. It would seem the spindle/ bearing would have to be quite bad to affect the sensors, and I cannot really tell of any problem. I already replaced the wire set as they recommended, which fixed a runability problem I had them check. Let's just say, with a half a dozen used Bonnevilles on the Pontiac lot, they may have been a bit bias on the diagnostics of the car from the Chevy lot? Thanks, Zzahh |
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The ABTCS system processor does a self check on all it's electrical circuits at startup, and another one at 2-8 MPH to check wheel speed sensors and cycle the pressure modulator solenoids. A failure at either of these checks disables the system and turns on the warning light. An intermittent loss of WSS signal can cause the system to repeat the self check at slow speeds. The right front is most common (guess which side most curbs are on), and the sensor is integral with the wheel bearing/hub assembly. Other causes can include a chafed through sensor harness, or a mis-routed harness causing harness strain when tight cornering. The appropriate repair strategy would be to correct the WSS condition (the sensor output can be checked on an oscilliscope to verify it's signal to the processor, before spending $200+ on a sensor/bearing/hub), clear any stored trouble codes, then road test to see if any other codes reset. There may be a pressure modulator problem, but WSS faults can set a lot of "ghost" codes. |
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| Well, I contacted the dealer found out the ABS diagnostic code was 74. This of course tells a layman like myself absolutely nothing, however, I will do a complete hub assembly inspection myself, and see what that nets me. | |
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DTC 74 is Pressure Modulator Valve pressure switch circuit failure. If, during a traction control event the brake pedal is depressed, the pressure switch signals the ABTCS control module to disable traction control and allow manual braking. The pressure switch is part of the Pressure Modulator Valve and is not serviced seperately. Possibilities: -circuit # 1659, control module teminal 13 to PMV connector 1, terminal 11, open or grounded -circuit # 853, PMV connector 1, terminal 12, to TCC/ABS switch (at brake pedal) open -failed pressure switch (or PMV internal switch circuit) These systems use a mylar circuit board at the PMV to carry signals to the solenoids and switches. Due to repeated heating and cooling, the mylar flexes and cracks can develop in circuit tracks. I've repaired lots of them by paralleling a wire across the broken track, from connector pin to pin. |
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| Well Alcan, thanks again, piece of cake. And here I thought it might be technical or difficult. Sounds like I may have to think about this for a bit................ | |
| HAHAHAHAHAHAHAHA......... sorry about that. I get carried away sometimes. OK, Reader's Digest version: The pressure switch is in the Pressure Modulator, and can't be serviced seperately. The switch might be defective, or there could be a problem in the wiring. The Bonneville factory manual has a diagnostic trouble tree for that trouble code, and any good tech who follows the tree EXACTLY (checking various circuits as the tree dictates) will locate the source of the problem. If it turns out to be the Pressure Modulator, it can usually be corrected if he's willing to open it up and do a circuit board repair. The diagnosis to determine the exact fault shouldn't cost more than 1 hr. labour, including checking all the associated circuitry. Make sure the shop has the appropriate year/model factory manual. | |
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Well Mr. Alcan, I must say you do sound like an asset to any service department. Believe it or not, I am quite capable mechanically, and after reading very closely what it is you have written, both the technical and the Readers Digest versions, I do get a picture. I believe with a manual that pointed out where these specific parts were, I could at least do a physical inspection for wear, damaged or cracked insulation, dirty connections, etc. Circuit board stuff would be an entire other issue, however, I have done some detailed electrical soldering in my day. Still sounds like a tech needs to diagnose the exact problem. Like I had said, the first diagnosis gave them the code 74, and their immediate answer was to toss $ 1,300.00+ worth of parts into the car. For right now, I am going to observe what I can, clean up what I can, and see what happens. There have been times in the past few days, when the lights have not come on for quite a few miles. Makes me wonder if it may be a connection somewhere. I know the ABS does work, because it comes on and growls occasionally when the car is barely even moving. I will keep note of all you have said, if nothing else it is ammo for the service department. Thanks again, and I look forward to more and better discussions through this medium. Zzahh |
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