1996 Dodge Neon TPS error, way too many things replaced ALR

AJRUTHERFORD

MEMBER
1996 DODGE NEON
4 CYL
2WD
MANUAL
135,000 MILES

This problem has been a plague for the better part of two years. At that time my car started hitching (literally hiccuping down the road) as though it were completely losing power. The Check Engine Light came on and was throwing a throttle position sensor error. A long diagnostic later my mechanic said "not the sensor", it was the computer. I replaced that and it ran fine. For a bit. It started up again, the exact same problem. Since then I've had a myriad of "solutions", including but not limited to: the starter, the crank sensor, the throttle sensor itself, the mass air flow sensor, the throttle position sensor and I even went through the wiring harness and rebuilt the thing. Yet the ghost is still in the car. A potentially related problem is that my console sometimes stops functioning entirely (no speed, throttle, anything). I've also replaced the console so I think I'm chasing a short somewhere, but I could be off base. Where do I go now?

3 Replies

JDL

MECHANIC
16,098 POSTS

Thanks for the donation, I saw what you replaced, still have to ask, How long since a tune-up? When the vehicle acts-up, use a fuel pressure gage, just to rule something out. What was the actual code number? I check sensor circuits first, before replacing anything. When there is a sensor code, if that sensor shares circuits with other sensors, like ref voltage and ground, I may check those also. Sometimes it's like hunting a needle in a haystack. If there is a problem that causes the computer to fail, if it isn't fixed, the new computer will fail, also. I'm not saying the computer has failed, again. I always start with basics, fuel--spark--timing--vacuum leak--egr, anything applicable.

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Friday, January 22nd, 2010 AT 1:44 PM

AJRUTHERFORD

MEMBER
6 POSTS

I've had to reset the computer (other work requiring the battery disconnected) so I can't get the code number until it acts up again, but I do know it was always telling me that the reference voltage was the particular fault. This is why so many electrical systems and sensors have been replaced.

As for what shares that voltage, the diagram I have shows. Well a LOT of other items that share that voltage, so needle in a haystack about covers the assessment nicely.

I do tuneups more regularly than necessary (spark plugs have been replaced 3 times in 2009, oil changes every 3,000 miles with a new filter) and I've recently replaced the fuel filter too (one of the first things we did). I'm going to have to look into vacuum leaks and egr. I think the fault is still electrical though, as the computer just went haywire on me and I had to reset it to get the car to turn on at all. The battery was fine and cold/running voltages checked out.

I personally fear that there's a fault in the wiring harness that crosses the car firewall. I have no idea how to pull it to get the thing fixed unlike the engine's electrical harness. I also don't have $1-2k to take it to the dealer for a detailed inspection and repair.

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Saturday, January 23rd, 2010 AT 2:13 PM

JDL

MECHANIC
16,098 POSTS

The tps and iat/map use the same ref voltage. Close to 5 volts, if you want to check, use digital multimeter. Key on, violet wire with white tracer. Also if the speedometer acts up, I'd have to check the vss. I'm not saying to replace anything, but, I would have to check the vehicle speed sensor.

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Saturday, January 23rd, 2010 AT 4:36 PM