1997 Volvo 960 sService Engine light

Tiny
JSEMPTD
  • MEMBER
  • 1997 VOLVO 960
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 142,457 MILES
My service Engine light stays on for maybe 1 minute after the engine is started immediately on entering the car. After that period the light goes out. If I turn the ignition switch on and wait for 30 seconds or more the light does not come on once the car is started. I have failed inspection with the vehicle. Their diagnosis is that the OBD system is not ready. How do I get the light to go out immediately upon starting so that I can over come tis problem?
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Saturday, October 17th, 2009 AT 7:49 AM

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Tiny
RACEFAN966
  • EXPERT
Ok the light will stay on for few seconds after starting. Now with your light staying on longer this is not right. Now I would like you to call around to your local parts stores and see if one will do a free scan. Have them scan it and write down the codes and then have them clear them. Get back to me with the what you find here.
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Saturday, October 17th, 2009 AT 8:45 AM
Tiny
MMPRINCE4000
  • EXPERT
Start by taking car to most autoparts stores and have any error codes read, if no codes you may have a problem with PCM.

Anytime light is on, PCM should store an error code.
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Saturday, October 17th, 2009 AT 8:46 AM
Tiny
JSEMPTD
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I have dne what you are suggesting. I have actually gone to three shops to have it checked for codes. Each visit at three different shops have returned the identical information. Nothing comes up as a code to suggest a fault. The readings are identical from each Test. System perfect, . No othing shiown that would indicate that there is a problem. The closest suggestion from one shop as to a problem is that I should change the ECU. That however I was told would nor guarantee a solution but a starting point. My response to that was that if we changed everything on the car eventually the problem would disappear. I know from my training that if you cannot identify the cause you certainly cannot find a solution. The suggestion you offer has been tried and paid for and no result found. Do you have any other ideas as to what might be the contributing factor to this issue?
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Saturday, October 17th, 2009 AT 9:24 AM
Tiny
JSEMPTD
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Saturday, October 17th, 2009 AT 9:50 PM
Tiny
JSEMPTD
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I have mentioned that three different shops have checked the vehicle. All three have returned the identical verdict. It is preposterous to assume that all three tests at different places can produce identical results and some genious would conclude that all thre different testis could indicate that there is a problem with the test instruments. This is certainly the apex of a graph on absurdity. Three tests at the same shop with the same instrument yes. Three tests at different locations across town all different test instruments and one would assert that the testing instrument s are all defective?. Please lets us not be that simplistic. Logic has a place in our world of thinking. Hurried conclusions without supportive facts or information NO NO NO. Tell me something that makes sense. I could have made an idiotic guess by myself without testing instruments and come up with an identical empty answer. That would not in and of itself have produced an answer to the problem. Let me reiterate. The test ahve not left any codes indicating that there is a problem with the car in any form or shape. If no code is left on any of the preceeding test then the logical conclusion is that there is no problem existing. If the tests did show a code on one occasion then the conclusion could be if the errror code dissapeared on a subsequent test that the problem is intermittent. These are difficult problems to pin down but no error code on thre seperate tests at different locations would suggest to me that there is something beyound what we are thinking. Could it be that for some reason that the computer is slow in the processing of iinformation fed into the system. Maybe I shall simply have to buy a new computer. What then if that does not solve the problem. Shoud I simply jettison the car as trash? That would take the problem away but someone with a similar issue down the road would not be able to definitively know what was the cause or what is the solution. I hope there exists out there somewhere in the Universe a giant who has a deeper understanding of the functioning priinciples of the logic systems installed in the cars we drive today.I wait for the brain to emerge from somewhere among us and not from outer space.
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Saturday, October 17th, 2009 AT 10:14 PM
Tiny
MMPRINCE4000
  • EXPERT
Yes is is highly unlikely that 3 shops would not get any error codes if they existed.

The check engine light is supposed to light up when the PCM sees a sensor out of a predefined range.

It is possible that the light has an intermittent short, causing it to illuminate.
I would check the wiring from light to the PCM, there may be a wire that is pinched or lost some insulation, causing a short to ground.

I would certainly not trash the car, if it is running OK, this may be a simple fix.

Generally when a PCM is bad, the car will not run or run very bad, and the PCM does and internal check evertime the ignition is turned on.
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Sunday, October 18th, 2009 AT 8:56 AM

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