PCM and moisture issues
#1
03-05-2019, 02:46 PM
Join Date: Jul 2018
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PCM, CCD buss, and moisture issues
Anyone else have an issue with the PCM malfunctioning in wet or very moist conditions? I have posted about the moisture issue before, but I am fairly (not totally) convinced that the PCM (or the connectors) is the culprit.
My deductive reasoning: I see the pattern.
1.Starts with airbag warning....constant...then
2. the airbag warning coincides with a speedo failure. They happen simultaneously.then
3. The tach starts to fail, followed shortly thereafter by the remaining guages.
When I let the truck cool down for an hour or so, problem goes away until it starts to run again....same sequence of events.
I have plugged an OBD II connector in, and I receive output information that the dash doesn't display. When the speedo fails, the odometer stops counting distance.
On only one occasion, the speedo was doing a self-test on it's own during this mayhem occurance, and triggered a speed sensor fault, which caused the engine to sputter and stall. Then it ran fine with the CEL illuminated, until I cleared the code.
Once the system has fully dried out, I get no more issue until it rains or fogs up again. I looked around for connection issues, but the harnesses (all 3 of them) route directly into the firewall without any connectors. The interior and under dash are dry. The PCM is directly exposed to head on rain or fog.
It's a 98 3.9L A/T
Anybody?
UPDATE: I ran a cluster check while the guages are inop, and I get all the CCD buss failure codes.900-950. Does the buss transmit from the PCM?
Is Flagship One a reputable company?
https://www.fs1inc.com/engine-comput...itional_tabbed
My deductive reasoning: I see the pattern.
1.Starts with airbag warning....constant...then
2. the airbag warning coincides with a speedo failure. They happen simultaneously.then
3. The tach starts to fail, followed shortly thereafter by the remaining guages.
When I let the truck cool down for an hour or so, problem goes away until it starts to run again....same sequence of events.
I have plugged an OBD II connector in, and I receive output information that the dash doesn't display. When the speedo fails, the odometer stops counting distance.
On only one occasion, the speedo was doing a self-test on it's own during this mayhem occurance, and triggered a speed sensor fault, which caused the engine to sputter and stall. Then it ran fine with the CEL illuminated, until I cleared the code.
Once the system has fully dried out, I get no more issue until it rains or fogs up again. I looked around for connection issues, but the harnesses (all 3 of them) route directly into the firewall without any connectors. The interior and under dash are dry. The PCM is directly exposed to head on rain or fog.
It's a 98 3.9L A/T
Anybody?
UPDATE: I ran a cluster check while the guages are inop, and I get all the CCD buss failure codes.900-950. Does the buss transmit from the PCM?
Is Flagship One a reputable company?
https://www.fs1inc.com/engine-comput...itional_tabbed
Last edited by restlessswind; 03-05-2019 at 05:14 PM.
#2
03-08-2019, 09:04 AM
Most everything is on the CCD bus. The PCM, The CTM, the cluster, the antilock brake controller (speed sensors), airbag system, etc.
The PCM is potted. But, given the amount of time and heat cycles anything is possible. Letting the truck cool down could indicate a solder joint failing too.
Not sure about a rebuilder.
The PCM is potted. But, given the amount of time and heat cycles anything is possible. Letting the truck cool down could indicate a solder joint failing too.
Not sure about a rebuilder.
