1991 Buick Lesabre codes

Tiny
PRECIOUSS043
  • MEMBER
  • 1991 BUICK LESABRE
  • 436,789 MILES
I had a diagnosis done on my Buick and I was wonder if anyone can tell me what these codes mean and what parts I need code 22, code 26, code27, code28, code29, code31. I try to see what parts to get plz help

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Wednesday, September 25th, 2013 AT 8:44 PM

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Tiny
CARADIODOC
  • EXPERT
22 - tps sensor signal voltage low

26 - quad-driver module (computer) circuit #1 fault

27 - quad-driver module (computer) 2nd gear circuit

28 - quad-driver module (computer) circuit #2 fault

29 - quad driver module (computer) 4th gear circuit

31 - cam position sensor fault

You can find the code definitions here:

http://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

You're making a very common mistake. Diagnostic fault codes never say to replace parts or that they're defective. They only indicate the circuits or systems that need further diagnosis. In the case of the quad drivers, there could be a problem with a computer module, and multiple codes leans more that way, but there could also be wiring problems. Look for corroded terminals in connectors, a wiring harness that fell down onto hot exhaust parts, or a harness that is rubbing on a sharp metal bracket.

Another cause of multiple codes is simply disconnecting a plug while the ignition switch is turned on. That can occur when moving things out of the way during other services, or when testing in a connector that has wires for many other circuits.

You didn't say why you had the codes read, or what the symptoms are. The throttle position sensor doesn't fail too often. Most commonly that code is set by unplugging it when the ignition switch is on. The camshaft position sensor can prevent the engine from starting depending on which engine you have. In the case of these codes, your mechanic will have a diagnostic manual that lists the steps to test each circuit. The first thing he will do, assuming the engine runs, is to record, then erase the codes, then see which ones set again. That will eliminate chasing false codes that someone else may have set inadvertently.
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Wednesday, September 25th, 2013 AT 11:01 PM
Tiny
PRECIOUSS043
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Ok thank u and yes the car runs well but when I'm randomly driving it jerks and hesitation sometimes I have to take my foot off the gas pedal and push down alittle harder and it stop jerking I don't have alot of problem out of it but I would like to get it fix before it becomes a bigger problem
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Wednesday, September 25th, 2013 AT 11:16 PM
Tiny
CARADIODOC
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Dandy. Since we know the codes, the next thing to do is erase them, then see which ones come back. When they do, if we still can't make sense out of them, and with such an intermittent problem, the next things is to drive the car with a scanner connected that has record capabilities. You press the "record" button when the hesitation or jerking occurs, then you can play it back slowly later to see what the sensors were reporting. Since the data passes through the scanner's memory, the recording actually starts a few seconds before you press the record button.

Intermittent electrical problems, like loose connections or a glitch in a sensor, can act up for too little time to find them with a voltmeter, but the Engine Computer will detect them. By playing a recording of what the computer sees, it gives you time to see a signal dropout or sudden change in its voltage reading.

In the case of the camshaft position sensor, it could be starting to fail, or there could be something like rust buildup on the magnet that is weakening the signal to the point the computer might not recognize it. There could be dirt in the throttle position sensor, but it is just as likely there's a loose terminal in its connector, or some other wiring issue related to that sensor. Most people replace a sensor and assume that's all it can be when there's a code related to it, but half the time the sensor is okay and the cause is something else with the wiring.
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Thursday, September 26th, 2013 AT 9:51 PM
Tiny
PRECIOUSS043
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I reset the computer and done the other stuff u told me everything was fine but it pull up codes 27 28 29 can u tell me how to look up the 5 digit trouble codes for the2 digit codes I have?
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Saturday, September 28th, 2013 AT 10:12 AM
Tiny
CARADIODOC
  • EXPERT
There aren't any five-digit codes, just two-digit codes. Three-digit codes started with '96 models with the on-board diagnostic system, version 2, (OBD2).

To do the diagnostics for a given code, you either need the specific diagnostic manual, which is different than the regular service manual, or, some scanners have a diagnostic chart built into their memory. You can also buy a subscription to one of the online service manual companies. The cost for one car model is pretty reasonable for one year or five years, especially compared to the thousands of dollars repair shops spend every year to subscribe. They have the diagnostic charts included.
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Sunday, September 29th, 2013 AT 8:33 PM

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