snakedoc67 Posted September 14, 2015 Share Posted September 14, 2015 Had a new CPS installed last week to try and resolve a crank but no start problem. The mechanic that did the work confirmed that the coil (new), ignition module (old) and CPS were working correctly and that power was getting to the ECU but the ECU was not sending a signal to the coil. Is there a test I can do with the ECU to determine if that is the cause as opposed to bad wiring? 87 Renix 4.0 Link to comment Share on other sites More sharing options...
metrictonner Posted September 15, 2015 Share Posted September 15, 2015 This happened to me and I thought it was a bad ECU. Turned out to be open contacts in the ECU connectors, another old truck problem. Took the 201 and 202 connectors apart and filed and crimped the contacts. The specific contact for the coil is D13 on the big plug. Since one is open, all should probably be rebuilt. After I figured out where the contact lock was on the first one the rest were easy to clean up. You might be able to test this by letting the ECU hang on the side of the transmission tunnel still connected. You can juggle the wires at the back of the connectors as you turn the key. Of course it could be a broken wire so you can test continuity between the D13 contact and the coil contact. I wouldn't take the 201 and 202 connectors apart without a connector diagram found in the Renix manual or Chilton or Haynes manual. You may screw up and loose track of whose on first. After I did mine my dash lit up like a christmas tree. I saw lights and needle movement I hadn't seen in years. I particularly liked how my fuel injectors seemed to quiet down and the thing ran cooler. Totally bizaaaaar. Old truck contact corrosion. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 16, 2015 Share Posted September 16, 2015 Had a new CPS installed last week to try and resolve a crank but no start problem. The mechanic that did the work confirmed that the coil (new), ignition module (old) and CPS were working correctly and that power was getting to the ECU but the ECU was not sending a signal to the coil. Is there a test I can do with the ECU to determine if that is the cause as opposed to bad wiring? 87 Renix 4.0 Have you eliminated the C101 yet? Link to comment Share on other sites More sharing options...
snakedoc67 Posted September 18, 2015 Author Share Posted September 18, 2015 thanks for the tips will try those and see, still have my C101 but have done most of the other Tips to include #2 Link to comment Share on other sites More sharing options...
cruiser54 Posted September 19, 2015 Share Posted September 19, 2015 As of the last year and a half, I have become quite the supporter of eliminating the C101. Link to comment Share on other sites More sharing options...
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