Yreka_Kid

It was the ECM - Issue solved

Hi All, I'm trying to help OP get this thing going. Its a bit of a mess so we are trying to work on one thing at a time. I'll try and add a bit more information here: Right now, we are trying to start with/tackle the lack of spark but any other advice on methodology or otherwise is welcome... - We have been doing quite a bit of searching/reading & have gathered the ECM itself is rarely the problem - trying to isolate as much as possible & eliminate all of the other possibilities before pulling the trigger trying to find another one. *Assumption based on research* - if we have 12VDC on the appropriate inputs, proper ground(s), and an appropriate ESS Signal at the ECU, we should see an output (ground?) from Pin27 (Orange black) at the diag con 1 and ICM -- I believe we have this, and yet we aren't seeing anything output. Here is what we have looked at/done so far. Starter cranks engine over fine - All of the fusible links off of the starter relay appear to be OK. We've done the "must do" from Cruiser 54 page (1-5) we saw mentioned quite a bit on all of the older problem threads - This truck being an 86 doesn't have the C101 so we did the connector behind the fuse box instead as it had plenty of the black tar stuff. Checking @ ECM connector Grounds @ pin 1 and 2 (Black) ECU OK continuity - I can't remember if we checked Resistance, but can double check The latch relay is never being triggered by the ECU so we've bypassed that to get 12V on Pin 19 (pink wire) -- ( I assume you should see a ground output on Pin 7 from the ECU to trigger this when the key is on and shortly after off? Its open all the time) 12VDC on Pin 4 (red) constant 12VDC on Pin 3 only with key on (Yellow) Truck is an MT so we have been ignoring Pin 12 (BlkWht) which I believe would prevent the truck from being started unless in Park or Neutral but maybe we need to verify ground here? Not sure if its relevant on the MT since the drawing lists A/T ~0.4 to 0.5VAC across Pin 11 (Vio/WHT) and 28 (WHT BLK) while cranking - this is a new sensor, the original was marginal @ about .3 so we replaced that. Removed cover to the ECM - caps etc look good - no corrosion on the connectors. Initially we were testing with a spark checker off the coil, but have since moved onto looking for a signal going into the coil/ICM which is not there.