1993 4.9L Computer Reset
Thread Starter
Member
Joined: Oct 2007
Posts: 39
Likes: 1
From: Florida
Does anyone know what the black electrical component (not the resistor) is and what purpose it serves? The reason I ask is that during my search for the remanuf ECM, I came across comments to the effect that:
"A fuel solenoid can start going bad gradually and cause the ECM voltage power supply output voltage to drop. This can lead to hard starting and eventually a no start condition.
This condition can also damage your ECM. Most the damage occurs when the engine is turned off, as the solenoid hangs up for a second and a voltage spike returns to the ECM and shorts it out. This can burn up the ECM circuitry and make it non-rebuildable."
The fuel gauges were erratic when I filled up the night before the ECM fried, but I did drive ~20 miles without noticing other symptoms. So now I'm on a quest to determine if the fluctuations were caused by a failing ECM (due to corrosion from a leaky electrolytic cap) or if the ECM failed due to a fuel solenoid issue. But knowing what that black component is will help my search. Thanks.
"A fuel solenoid can start going bad gradually and cause the ECM voltage power supply output voltage to drop. This can lead to hard starting and eventually a no start condition.
This condition can also damage your ECM. Most the damage occurs when the engine is turned off, as the solenoid hangs up for a second and a voltage spike returns to the ECM and shorts it out. This can burn up the ECM circuitry and make it non-rebuildable."
The fuel gauges were erratic when I filled up the night before the ECM fried, but I did drive ~20 miles without noticing other symptoms. So now I'm on a quest to determine if the fluctuations were caused by a failing ECM (due to corrosion from a leaky electrolytic cap) or if the ECM failed due to a fuel solenoid issue. But knowing what that black component is will help my search. Thanks.
Thread Starter
Member
Joined: Oct 2007
Posts: 39
Likes: 1
From: Florida
Replacement ECM
I opted to purchase an ECM on eBay, since I would be out less money if the failure was a result of the most recent problem. The seller agreed to let me open the chassis and inspect for signs of potential problems. As you can see, 1 of 3 caps is leaking, and this happens to be the cap near my most recent fail site. The leaky cap is near the VPWR pins, so it makes sense that my truck came to an abrupt halt when it failed. I'm going to try out the ECM and then replace the caps to ensure they'll be healthy for at least a few more years.
Not to beat a dead horse, but these images of the "new" ECM illustrate this is a recurring problem with the ECMs. Other people that I talked to in the refurb/remfg (R & R) business confirmed that the "high fail rate" items they replace are these caps. Leaky caps have also caused numerous home PC failures in the past, so the electrolytic fluid is definitely caustic to PCB traces.
Not to beat a dead horse, but these images of the "new" ECM illustrate this is a recurring problem with the ECMs. Other people that I talked to in the refurb/remfg (R & R) business confirmed that the "high fail rate" items they replace are these caps. Leaky caps have also caused numerous home PC failures in the past, so the electrolytic fluid is definitely caustic to PCB traces.
Old Bastard
Joined: Oct 2009
Posts: 587
Likes: 2
From: Macomb, IL
Originally Posted by DFFECHSWU
I opted to purchase an ECM on eBay, since I would be out less money if the failure was a result of the most recent problem. The seller agreed to let me open the chassis and inspect for signs of potential problems. As you can see, 1 of 3 caps is leaking, and this happens to be the cap near my most recent fail site. The leaky cap is near the VPWR pins, so it makes sense that my truck came to an abrupt halt when it failed. I'm going to try out the ECM and then replace the caps to ensure they'll be healthy for at least a few more years.
Not to beat a dead horse, but these images of the "new" ECM illustrate this is a recurring problem with the ECMs. Other people that I talked to in the refurb/remfg (R & R) business confirmed that the "high fail rate" items they replace are these caps. Leaky caps have also caused numerous home PC failures in the past, so the electrolytic fluid is definitely caustic to PCB traces.
Not to beat a dead horse, but these images of the "new" ECM illustrate this is a recurring problem with the ECMs. Other people that I talked to in the refurb/remfg (R & R) business confirmed that the "high fail rate" items they replace are these caps. Leaky caps have also caused numerous home PC failures in the past, so the electrolytic fluid is definitely caustic to PCB traces.