If I drive the car on the interstate for 15-30 min and turn the car off , it won’t start back up and gives the impression of a dying battery, I determined that it’s the ecm that dies. Replace it with another and it’s good to go. What gives? Grounds?
Ecm keeps dying after long drive
- Thread starter sdteb
- Start date
TIMINATOR
Well-Known Member
- Joined
- Jan 26, 2020
Look at output voltage of the alternator. Alternators are 3 phase and most make around 100 to 130 AC volts at higher RPMs!!!!!!
If the regulator is bad or is poorly grounded, voltage can go high, and if any one of the diode trio shorts, (there are 6 of them) then an AC component superimposes itself on the normally DC output. That can fry lots of stuff!
If you know someone, or a shop, with an oscilloscope, probe the alternators output terminal and look for AC ripple on it. Its easy to see. Bad connections and grounds can also cause voltage spikes that will also fry things.
Uh, ya don't happen to have low impedance injectors in yer motor with a stock computer, do ya?
Just a few things to look at....
TIMINATOR
If the regulator is bad or is poorly grounded, voltage can go high, and if any one of the diode trio shorts, (there are 6 of them) then an AC component superimposes itself on the normally DC output. That can fry lots of stuff!
If you know someone, or a shop, with an oscilloscope, probe the alternators output terminal and look for AC ripple on it. Its easy to see. Bad connections and grounds can also cause voltage spikes that will also fry things.
Uh, ya don't happen to have low impedance injectors in yer motor with a stock computer, do ya?
Just a few things to look at....
TIMINATOR
No just 60lb injectors.
- Joined
- May 28, 2001
What Tim said: "and if any one of the diode trio shorts, (there are 6 of them) then an AC component superimposes itself on the normally DC output".
Also, once the "dead" ecm is changed out, can it be re-used later?
Any SM or PL logs of this happening?
TIMINATOR
Well-Known Member
- Joined
- Jan 26, 2020
You can have it tested, but its not likely that it "fixed itself." If it tests good, it probably is and was. Perhaps a bad connection at the ECM plug. Did you clean all of the ECM and connector pins? Did you do a wiggle test AFTER you replaced the ECM? You need to quit throwing parts at it and find the cause.
Also, not to be macabre, but like a heart attack "from out of the blue" that killed you, everything seemed to be going OK, until you died. Something occurred, it maybe (you aren't SURE yet) killed the ECM, find the cause. Changing the ECM is treating the symptoms.
TIMINATOR
Also, not to be macabre, but like a heart attack "from out of the blue" that killed you, everything seemed to be going OK, until you died. Something occurred, it maybe (you aren't SURE yet) killed the ECM, find the cause. Changing the ECM is treating the symptoms.
TIMINATOR
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