flufrooster Posted October 30, 2014 Share Posted October 30, 2014 I bought a 1991 Comanche that has a 1988 Cherokee 4.0 in it. I can get it to crank, but no fire. The crank sensor plug has power to it, but the plug on the wiring harness is different than the one on the motor. The wiring harness has three wires, the other has two. Any ideas? Link to comment Share on other sites More sharing options...
Jeep Driver Posted October 30, 2014 Share Posted October 30, 2014 Get a CPS for a 91 Link to comment Share on other sites More sharing options...
flufrooster Posted October 30, 2014 Author Share Posted October 30, 2014 That was my thought, but I wasn't sure if they were interchangeable. Thanks Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 30, 2014 Share Posted October 30, 2014 Does the 88 engine have a 91 and up HO flywheel / flexplate (you didn't say if it was an auto or stick)? If not, it still will not run with a new HO CPS. Link to comment Share on other sites More sharing options...
flufrooster Posted October 30, 2014 Author Share Posted October 30, 2014 The motor and transmission are both 88, and it's automatic. We're trying to plug this all into the 91 wiring harness. Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 30, 2014 Share Posted October 30, 2014 The motor and transmission are both 88, and it's automatic. We're trying to plug this all into the 91 wiring harness. As before, if using your 91 Chrysler electronics system, including the 3-wire 91 CPS it has to have, you will need to swap out your 88 Renix flexplate with a 91 and up HO flexplate. The 91 HO Chrysler CPS will not read the Renix flexplate pulse ring. You will also need the HO engine harness, HO sensors, throttle body, and distributor installed to feed the HO computer. Link to comment Share on other sites More sharing options...
flufrooster Posted October 30, 2014 Author Share Posted October 30, 2014 Would it be easier to swap computers? I am a old ford guy, so everything is carbs. This stuff is all new to me. Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 30, 2014 Share Posted October 30, 2014 The computer must match the harness and sensors. Therefore swapping the HO computer for the Renix computer will also require swapping the entire underhood harness, using all the Renix sensors, then figuring out how to mate the Renix harness with the 91 HO body harnesses. Tough job. BUT, you could also use the existing Renix flexplate with this configuration. To me that would be taking a step backward and counterproductive. I'd use the 88 Renix block with the HO sensors, HO head, HO throttle body, and HO flex plate. Link to comment Share on other sites More sharing options...
flufrooster Posted October 31, 2014 Author Share Posted October 31, 2014 We will go on a parts hunt and change this one up then. Thanks Link to comment Share on other sites More sharing options...
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