ECU Testing, intermittent crank no start
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Driver School Candidate
Joined: Apr 2022
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From: Texas
ECU Testing, intermittent crank no start
I have a 1993 Sc400 that I recently acquired. For the past two weeks, occasionally it will not start, it cranks strong but I don’t hear the fuel system prime. The EFI Relay clicks on every time, fuel pump ecu has already been deleted. Jumping pin FP to B+ does not work. I think my next logical step would be to rest the pins on the ecu to see if they are receiving power. I have a power probe and I was hoping for some guidance on how to test the ecu. I’ve noticed that if the CEL light does not come on in accessory mode then the car will not start. Any suggestions?
Thread Starter
Driver School Candidate
Joined: Apr 2022
Posts: 3
Likes: 0
From: Texas
ECU Diagnosis help needed. Need a pin out, PO splice wires into ecu harness
I have a 1993 Sc400 that I recently acquired. For the past two weeks, occasionally it will not start, it cranks strong but I don’t hear the fuel system prime. The EFI Relay clicks on every time, fuel pump ecu has already been deleted. Jumping pin FP to B+ does not work. I think my next logical step would be to rest the pins on the ecu to see if they are receiving power. I have a power probe and I was hoping for some guidance on how to test the ecu. I’ve noticed that if the CEL light does not come on in accessory mode then the car will not start. Any suggestions?
Pin 29 & 30 have been spliced with speaker wire, what do they go to in the ECU. I have the lextreme ecu diagrams but I’m not all too sure how to read them.
Thread Starter
Driver School Candidate
Joined: Apr 2022
Posts: 3
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From: Texas
I cracked it open last night, and there was a little fluid on some of the capacitors. I sent it out to get rebuilt. We will see what they find. But I’m still curious what those pins go to. They are pin 29 & 30 in the middle plug. But the ecu diagrams from lextreme don’t have a pin 29 or 30
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