No ignition signal to ICM, no spark
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CF Beginner
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No ignition signal to ICM, no spark
Hello Folks,
1998 GMC 1500 Van with the 5.7 Vortec
Van was dying intermittently, felt like an electrical issue, entire dash would flash, ABS light was acting weird, etc. Did this for 20 minutes, could restart and nurse it, and it would conk out all together, then it died completely, would still crank all day, just no start.
Tested everything, had spark at that time, from the coil and at the wires coming out of the distributor. Had low fuel pressure, in the 40s, so I replaced the fuel pump.
Once new pump is in, fuel pressure is great, now there's no spark.
No spark coming from the coil.
- 12 volts coming to pink wire to Coil and ICM.
- ICM ground wire is good.
- No signal to coil or ICM trigger signal wires.
- Test Crank Position Sensor, it has power and is cycling from 0 to 5 volts as I slowly turn over engine, so it's good.
- Test wire from CPS to ECM, wire is fine, has continuity.
- Test wire from ICM to ECM, wire is fine, has continuity.
- All fuses to ECM are fine.
The only other wrinkle is that the ECM is throwing no codes, and it definitely had codes on it before the van died (I have a pretty regular misfire that keeps the light on). Now it won't even connect to the OBD II code reader, it says "NO LINK" and i've tried two code readers that both worked before.
Is it a bad ECM? I've heard this is rare?
Anything I missed?
1998 GMC 1500 Van with the 5.7 Vortec
Van was dying intermittently, felt like an electrical issue, entire dash would flash, ABS light was acting weird, etc. Did this for 20 minutes, could restart and nurse it, and it would conk out all together, then it died completely, would still crank all day, just no start.
Tested everything, had spark at that time, from the coil and at the wires coming out of the distributor. Had low fuel pressure, in the 40s, so I replaced the fuel pump.
Once new pump is in, fuel pressure is great, now there's no spark.
No spark coming from the coil.
- 12 volts coming to pink wire to Coil and ICM.
- ICM ground wire is good.
- No signal to coil or ICM trigger signal wires.
- Test Crank Position Sensor, it has power and is cycling from 0 to 5 volts as I slowly turn over engine, so it's good.
- Test wire from CPS to ECM, wire is fine, has continuity.
- Test wire from ICM to ECM, wire is fine, has continuity.
- All fuses to ECM are fine.
The only other wrinkle is that the ECM is throwing no codes, and it definitely had codes on it before the van died (I have a pretty regular misfire that keeps the light on). Now it won't even connect to the OBD II code reader, it says "NO LINK" and i've tried two code readers that both worked before.
Is it a bad ECM? I've heard this is rare?
Anything I missed?
CF Monarch
Joined: Oct 2017
Posts: 4,605
Likes: 269
From: USA
Hello Folks,
1998 GMC 1500 Van with the 5.7 Vortec
Van was dying intermittently, felt like an electrical issue, entire dash would flash, ABS light was acting weird, etc. Did this for 20 minutes, could restart and nurse it, and it would conk out all together, then it died completely, would still crank all day, just no start.
Tested everything, had spark at that time, from the coil and at the wires coming out of the distributor. Had low fuel pressure, in the 40s, so I replaced the fuel pump.
Once new pump is in, fuel pressure is great, now there's no spark.
No spark coming from the coil.
- 12 volts coming to pink wire to Coil and ICM.
- ICM ground wire is good.
- No signal to coil or ICM trigger signal wires.
- Test Crank Position Sensor, it has power and is cycling from 0 to 5 volts as I slowly turn over engine, so it's good.
- Test wire from CPS to ECM, wire is fine, has continuity.
- Test wire from ICM to ECM, wire is fine, has continuity.
- All fuses to ECM are fine.
The only other wrinkle is that the ECM is throwing no codes, and it definitely had codes on it before the van died (I have a pretty regular misfire that keeps the light on). Now it won't even connect to the OBD II code reader, it says "NO LINK" and i've tried two code readers that both worked before.
Is it a bad ECM? I've heard this is rare?
Anything I missed?
1998 GMC 1500 Van with the 5.7 Vortec
Van was dying intermittently, felt like an electrical issue, entire dash would flash, ABS light was acting weird, etc. Did this for 20 minutes, could restart and nurse it, and it would conk out all together, then it died completely, would still crank all day, just no start.
Tested everything, had spark at that time, from the coil and at the wires coming out of the distributor. Had low fuel pressure, in the 40s, so I replaced the fuel pump.
Once new pump is in, fuel pressure is great, now there's no spark.
No spark coming from the coil.
- 12 volts coming to pink wire to Coil and ICM.
- ICM ground wire is good.
- No signal to coil or ICM trigger signal wires.
- Test Crank Position Sensor, it has power and is cycling from 0 to 5 volts as I slowly turn over engine, so it's good.
- Test wire from CPS to ECM, wire is fine, has continuity.
- Test wire from ICM to ECM, wire is fine, has continuity.
- All fuses to ECM are fine.
The only other wrinkle is that the ECM is throwing no codes, and it definitely had codes on it before the van died (I have a pretty regular misfire that keeps the light on). Now it won't even connect to the OBD II code reader, it says "NO LINK" and i've tried two code readers that both worked before.
Is it a bad ECM? I've heard this is rare?
Anything I missed?
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darrenbrigman
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Oct 24, 2018 4:18 PM