Gouda Posted April 20, 2022 Share Posted April 20, 2022 I'm having a weird CPS issue that I'm hoping something else has run into before. A couple months ago the original CPS wiring became so brittle that it broke off at the sensor. I thought "No big deal, I'll just replace it." Put a new sensor on and initially everything worked perfectly. A couple days later I go to use the truck and nothing, spin no start. REMII reading 0 rpm while cranking. Tested resistance and while it seemed good I figured maybe I just had a poor quality new sensor. Looked online and found a different brand high altitude CPS. When it showed up, after replacing the battery (someone may have left the lights on, one of life's little mystery's) installed the new sensor and again runs great. Take it for a drive and it runs like a scalded dog. A couple days later, spin no start again. REMII reading 0 rpm while cranking. Good voltage at battery, no voltage drop along cables, good grounds. Checked that I didn't have pins pushed back or spread in connector. Tested AC voltage coming from sensor, right where it should be. Tested voltage on harness side, and after that it miraculously cranks right up and runs without any issues. Next day spin no start until I test voltage and then it fires up. I'm perplexed to say the least. I was thinking maybe an issue in the ecu so I have one coming but I'm all ears if someone has any other ideas Link to comment Share on other sites More sharing options...
JMO413 Posted April 20, 2022 Share Posted April 20, 2022 This will help everyone with what your working on. http://cruiser54.com/ Step #5 is my guess. 1-5 are all a must. Link to comment Share on other sites More sharing options...
Gouda Posted April 21, 2022 Author Share Posted April 21, 2022 I'll definitely give this a shot tomorrow when I can bring some better tools home from work. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 21, 2022 Share Posted April 21, 2022 Is yours an 88 or earlier? The CPS signal goes through that wonky C101 connector. http://cruiser54.com/?p=24 Link to comment Share on other sites More sharing options...
Gouda Posted April 21, 2022 Author Share Posted April 21, 2022 I came across an old TSB last night during my searching (Chrysler Service Bulletin 18-51-88) dealing with spin no start conditions like mine, so when I got home I ran 2 wires directly from the ECU to the CPS and voila problem appears to be solved. I had bypassed the C101 some time back so I think that I must have had a bad connection when I did it. I used solder heat shrink, maybe the solder didn't melt fully or cracked or something. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 22, 2022 Share Posted April 22, 2022 Nice job. Link to comment Share on other sites More sharing options...
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