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CPS TROUBLES AGAIN!!!!!

T

The Lure Washer

NAXJA Forum User
Location
Bristol, CT
This is the second CPS ive put in in the last 2 months. The second of which went in a week ago. Well my 1990renix POS doesnt start again and theres no spark coming of the coil. The coil is brand new as well. So why or what is causing this? Both of the CPS's came from Advanced auto.
 
The CPS is tested by ohms, if the resistance isn't high in the CPS itself, maybe the excess resistance is in the wiring or connectors.
I've had all sorts of wiring, connector and ground grief in my Renixes.
Not sure about the 90, but in earlier Renix models there was actually a patch kit to shorten the CPS wires to the ECU and bypass the harness.
There is hope though, my Renix now idles fine, never misses a beat, is as fast as my HO and thumps on down the road just fine. It took me a good long awhile with an ohm meter to find and fix all the excess resistance in the harnesses, connectors and get good grounds for most all of my sensors.
 
Last edited:
The Lure Washer said:
The sensor's resistance is 197 ohms but thats cold. Doesnt the resistance change as the engine gets warmer?
Click to expand...
It sure can, but the change doesn't seem constant from one CPS to the next. I had one CPS that crapped out at a certain temperature and often at almost exactly the same spot on the road to work.
You may have to ohm test the connector itself and then maybe the wiring from the CPS connector to the ECU.
I had a TPS connector that somebody had sprayed with WD-40 (figured that out by the smell) that really screwed with my TPS adjustment/values until I finally figured it out.
The pins on the ECU connector have a tendency to slide out of the connector body and barley make contact at all. I've seen that numerous times on ECU and TCU connector plugs.
 
197 ohms is within spec for the sensor. I agree that the connector may be suspect here (or wiring). The fact that you once had luck with getting it to work by unplugging/plugging it back in smells of a connectivity issue.

I'd clean the connector with electrical contact cleaner and perform a very careful inspection of all.
 
So I replaced the CPS with a mopar one, eliminated the connector and still doesnt start. Also replaced the ICM with a known good one. Went through all the relays and checked them via FSM. Also Swapped out Distributors. I get nothing but crank and crank and crank. Checked out the battery and gave it a charge. Where do i go from here? Is there some way I can check the computer. That is my next idea? As far as that im out of ideas.
 
A scan tool would tell you whether the crank signal is there or not. Have you tried cleaning the crank sensor connector inside the engine bay near the firewall #6 injector? It is an area where the crank sensor signal sometimes is inhibited due to corrosion, etc. Before I'd get a new computer, I'd be darn sure that the crank sensor is making it all the way TO the computer.
 
Scan tools are not easy to find for a Renix.

Are the injectors firing? If they are, then its not the CPS. If they aren't, it wasn't the ICM. You checked and swapped relays to eliminate a bad relay? Check for power at the injectors and ICM to eliminate a power problem? Ground strap at the firewall in good condition? Battery charged up, as the ICM will not fire is the voltage is too low.
 
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