Good evening. My son's 89 Ranger was running great. He got home from work, pulled in and shut it off. The next morning he got up to go to work and it wouldn't start so he took my car. I took a look at it, wiggled the wires that go to the ICM and it started right up. The next day he tried to start it and it would not start, again. For the sake of brevity, I followed a diagnostic chart that showed the ICM was bad. I replaced the ICM, then the exhaust side coil. still will not start reliably. When I can get it to start it runs great. The problem is getting it to start. Wiggling the wires can unreliably get it to start. I'm thinking of replacing the connectors that go to the ICM., but It appears I can only get one, I think the bottom connector. My questions are, 1 does anyone know where I can get both connectors? 2 am I barking up the wrong tree here?

 

Welcome to the forum

1989-1994 2.3l used the ICM unit for spark, its on the front end of the lower intake right behind the fan
Yes, these run hot and are known to fail

They also were known to lose chassis Ground, grounded by the 3 screws that hold it to the lower intake
These were known to rust out and cause starting/running issues

You put a new one on and did you clean or replace the 3 screws, and get all 3 back in place, the old ones like to break off, lol
I think the one or two on passenger side were the chassis grounds, if memory serves, so at least one of those must be a good ground, some people add a ground wire to one of those screws just to be sure

Crank sensor, its starts everything, no crank sensor pulse and no spark, or anything else, computer also use it to time injectors
Crank sensor wires come out the back of the timing belt cover on drivers side, round 4 wire connector, and plug into the ICMs wiring harness
Unplug its 4 wire connector and check it, then plug it back in, this cleans the contacts

Never tried to get connectors for these, but they are the same connectors at both ends, just different wires
Connectors were never an issue as far as breaking, just brittle wires and dirty pins

 

Thank you for responding. I completely agree with you 1st two paragraphs. Yes the ICM is grounded through the screws, There are 4 of them, yes I cleaned them and even replaced the heat sink paste on the back. I did run an external ground wire from the lower passenger side screw to the block. I checked wire #7 to ensure it was an active ground. I forgot to mention I was an ASE Certified Master Technician in the mid 80's but I worked at a Plymouth dealer so not a lot of Ford experience. I disagree with you last paragraph, the connectors are not the same. The alignment pin is on opposite sides to keep them from being plugged in backwards
But thank you for taking the time to respond, I do appreciate it.

 

Didn't realize about the connectors, good info, thanks

What about the Crank sensor plug in?

 

It passed the spin test. Here is what i thought was the answer. This test is what I based ordering a new ICM from.
https://easyautodiagnostics.com/ford...sensor-tests-1
I just found the other connector. Both are Standard Motor Products The Black one (Top) is S546 and the Gray one (Bottom) is S544. I'll solder them in when they arrive let everyone how it works out.

 

Does it have a CEL(check engine light) or a Tach?

CEL should come on after computer boots up
CEL should go OFF when engine is turning, this means computer is getting a good timing signal from crank sensor via ICM

Tach, of course, should show a change when cranking

 

No Tach. The CEL works as described.
Thanks