meir
OBS Enthusiast
that was my first thought. but i do have a spark.
can it be that the ignition module is bad in a way that i have a spark but no pulse for the ECU?
i do have an extra module. might give it a try.
engine cranks, won't start.
- Thread starter meir
- Start date
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can it be that the ignition module is bad in a way that i have a spark but no pulse for the ECU?
i do have an extra module. might give it a try.
meir
OBS Enthusiast
LOL. i'll do that next time.
evilunclegrimace
Does not always play well with others
You need to stop!!!! You are using the wrong chart and you are getting way ahead of your self. You need to start with Chart A-1 as follows.
First, do you have a SES light with the key on? if NOT you need to check for 12 volts to the ECM. Fuse "B" and/or the fusible link that feeds circuit 440( orange wire/wires ). IF the fusible link and the ECM "B" fuse are OK disconnect the ECM connectors and probe Circuit 440(Cavities C 16 and B 1) and circuit 439 pink/black wire ( cavity A 6) with a test light to ground. IF both circuts test good you have one of 2 things wrong. The ECM ground is faulty or the ECM has failed. Run these checks and let me know the out come. I have a copy of the 1989 Fuel and Driveability manual and can give you the steps to follow if you would like.
First, do you have a SES light with the key on? if NOT you need to check for 12 volts to the ECM. Fuse "B" and/or the fusible link that feeds circuit 440( orange wire/wires ). IF the fusible link and the ECM "B" fuse are OK disconnect the ECM connectors and probe Circuit 440(Cavities C 16 and B 1) and circuit 439 pink/black wire ( cavity A 6) with a test light to ground. IF both circuts test good you have one of 2 things wrong. The ECM ground is faulty or the ECM has failed. Run these checks and let me know the out come. I have a copy of the 1989 Fuel and Driveability manual and can give you the steps to follow if you would like.
meir
OBS Enthusiast
thank you Sir. i will do just that.
i did not touch the truck yet. hopefully this weekend.
i also ordered the book, but it will be here only next week.
the steps you described is exactly what i was looking for.
i will follow your instructions and will update over the weekend.
i already checked the fuses, but i will do it again. fuse B (i assume) is the 10 amp ECM fuse located in the fuse box under the steering.
what is the "fusible link that feeds circuit 440?
thanks in advance.
Meir.
evilunclegrimace
Does not always play well with others
The fusible links are under the "T" shaped plastic cover where the fuel pump relay is located. Make sure that the studs under the cover are not corroded and that the ground is good.
meir
OBS Enthusiast
perfect.
that's the first place i was looking at. all looks good down there.
just a thought though. if i had issue with power supply to the ECU, would i'll be also losing spark?
which also make doubt my theory on having a bad ignition module. if the module is not providing puls to the ECU on cranking (to make the ECU activate the pump), will i still have a spark?
regardless, i will follow your instructions, and will also measure continuity using a voltmeter between A1 on the ECU and 465 on the relay. just to make sure the green/white wire is not interrupted or shorted.
RedLeader289
OBS Enthusiast
If the engine was running fine why were you messing with the timing?
It sounds like you unplugged the ICM.
Pull the #1 spark plug, ground it out, and have someone crank the engine. If it doesn't spark then your ICM is either unplugged or has failed.
It sounds like you unplugged the ICM.
Pull the #1 spark plug, ground it out, and have someone crank the engine. If it doesn't spark then your ICM is either unplugged or has failed.
meir
OBS Enthusiast
got brand new distributor with brand new ICM and wires, and brand new coil. all replaced about a month ago.
got spark on cylinder 1.
engine was running a bit rich, so i wanted to get it back to 0 advance.
TD Henley
Newbie
I would check the oil pressure sending unit first. Unplug it and jump the two wires and see if that turns the pump on.
joep88cheyenne
I'm Awesome
I'm gonna ask a odd question, did you recoonect the wire and see if it started? Just my typical thought train running " I unplugged that wire and it won't start, maybe it will start when I plug it back" troubleshooting method.
