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Discussion Starter #1
First off I want to say thanks in advance for anyone who helps me here. This is my first post here and I'm glad to have finally made an account. I've used the forum as a source of information for a while, but I haven't been able to find the answers I'm looking for with the search engine this time...

I have a '95 Caprice 4.3L Sedan, and I am beginning to get the impression that my trouble codes can only be obtained through a very specific scanner, or an ALDL cable to software on a laptop/phone. Is this correct?

I have tried the trick of "jumping" the pins on the OBD1 plug, the cooling fans come on and the check engine light (CEL) stays on. I purchased a scanner for GM OBD1 cars of my year that AutoZone said was compatible, but the same thing happens. Here's a link to the scanner I bought: INNOVA 3123

My CEL is coming on while driving, after about 5 minutes or when my engine warms up. This happens immediately after I feel a small bump, like it's shifting gears, and when this happens, my car acts like it's got the scanner or the jumper wire on the OBD1 port... the fans both come on and additionally, I start getting TERRIBLE fuel economy. I'm spending twice as much on gas as I used to since this began.

One interesting observation, this seems to come and go sometimes. Only thing to note about this is that the CEL seems to go off more often when it's colder outside. Cold being a relative term, since I live in FL. Also, and I doubt this has anything to do with it, but it seems to go away while driving more often when I have a full tank of gas as well.

Any information at all, even speculation would be appreciated. I know this is the place to be asking!

-Jacob
 

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Looks like your scanner should give you all the codes the PCM is triggering.
you said codes but only gave us one ?
sounds like you did the first option and it did not work
you will need to check the other 6.

Bad ECT sensor
Short to ground on ECT signal circuit
Faulty or damaged connectors
Wiring harness damaged
Loose terminals at ECT or PCM
POSSIBLY an overheated engine
Bad PCM

From your symptoms sounds like it runs fine in open-loop and then when warms up and goes
to closed-loop is runs like crap.

Maybe google if Torque app works on OBD-1 ????
you likely need to scan and data log while car is running and warmed up to see if the problem is deeper
than just the ECT.

i am not too knowledgeable cuz i have a '96 with obd-II
Good Luck.
-ALF out....
 

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Discussion Starter #4
Thank you for your response. The trouble code that I listed what simply obtained by doing a google search for my car's symptoms. It was not obtained using a scanner, as I am now certain that I may only obtain trouble codes through in ALDL cable, I have ordered the parts I need to make one. I will start another thread about that when it arrives.

I do now believe more than ever that my problem is being caused by a temperature sensor, or the wiring connected to it. I recently had to cut and splice wire to remove some bad spots on my wiring harness below the steering column. Dunno if that could affect anything, but I will look into that next as I wait on my diagnostic cable, and make sure that all my connections are good.

Thanks again!
 
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