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spw4646
New User
Dec 3, 2013, 10:45 AM
Post #1 of 5
(2520 views)
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I have a 95 dodge neon, 2.0 sohc, 5 spd. I put a head gasket, water pump, and timing belt in it and it ran great until I pressure washed the engine bay. I know its a dumb thing to do but I never gave it a second thought at the time. I ended up with a code of P0123 (tps circuit A high voltage). I started troubleshooting the tps and have 5v on the reference wire, ground is good, but I had 4.6v in the signal wire. This was all tested by back probing the connector while plugged into the tps. I pulled the signal wire out of the tps connector and out of the pcm connector so both ends were disconnected and checked it for voltage to see if it is shorted to the reference wire. 0v, no short. I pushed a test wire through the pcm connector on to pin #10, the signal wire pin, and have 4.6v coming out of the pcm where the tps signal voltage should go in.
I got a junk yard pcm and have all the same problems except I get 4.9v instead of 4.6 and now my tps is fried. I got a new tps but don't want to fry it. Is it possible that I got a bad pcm from the junk yard that has the exact same problem as the original?
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DanD
Veteran
/ Moderator
Dec 3, 2013, 11:50 AM
Post #2 of 5
(2499 views)
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Re: PCM?? 95 neon
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The odds are quite unlikely that 2 PCM have the exact same issue but you never know when it comes out of a junk yard?
Your tests do sound valid, there shouldn't be any or very little residual voltage on the signal return?
After doing some reading and your info that your issues started after power washing; try disconnecting the TCM (transmission control module) if it an auto matic; it also used TPS signal.
Let me know what you find.
Dan.
Never mind about the TCM I didn't see the "5'speed"
Canadian "EH"
(This post was edited by DanD on Dec 3, 2013, 11:52 AM)
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DanD
Veteran
/ Moderator
Dec 3, 2013, 12:03 PM
Post #3 of 5
(2492 views)
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Re: PCM?? 95 neon
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Sorry for the double post; but maybe start testing signal return from other sensors?
There could be a splice somewhere that is feeding reference voltage back into TPS return?
Dan
Canadian "EH"
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spw4646
New User
Dec 3, 2013, 12:05 PM
Post #4 of 5
(2490 views)
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Re: PCM?? 95 neon
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Thanks for the reply. It seemed unlikely to me that a second pcm would have the same problem but I had it picked up for me at the yard and know nothing about the vehicle it came out of. It's the same part number so I know it's the correct pcm..
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DanD
Veteran
/ Moderator
Dec 3, 2013, 12:59 PM
Post #5 of 5
(2488 views)
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Re: PCM?? 95 neon
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I would talk to the people at the yard you got the PCM from and explain your situation. Most times if they want to listen they'll help out and let you try another PCM.
Like I said your testing sounds valid.
Dan.
Canadian "EH"
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