Strange electrical problems...
#1
10-18-2006, 03:15 PM
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Strange electrical problems...
I've got a '97 F150--XL trim--not much in the way of fancy electronics. I first had this problem about 4 months ago and the symtoms went away by themselves until yesterday. Some of the symtoms are back and new symptoms have appeared. Here are the clues:
Noticed sometime after a rain. (both occurrences)
Noticed a very small amount of dirty water on the psgr side floor coming from near the firewall area, I think. Does NOT appear to be coolant.
With the ignition switch in the OFF position, and the AC switch in the AC position, the fan continues to run at very slow speed. When the AC sw is moved to OFF, the uncommanded fan operation stops. (both occurrences)
The check airbag symbol appeared and stayed on steady (both occurrences; it was reset by dealer the first time)
With Ign sw OFF, clicking from under the dash found to be coming from the turn signal relay thing--with ign sw RUN turn signals worked normally with no unusual clicking. (first occurrence only)
Speedometer remains at zero regardless of speed. Odometer doesn't moves either. (second occurrence only)
Windshield wipers intermittently responsive to switch position--no real pattern. Once they got going, they worked OK. (second occurrence only)
Seat belt warning light appeared when it shouldn't have, then went out (second occurrence only)
No other electrical components have displayed problems yet. Engine works normally, idles fine.
What I think....small water leak somewhere in the cowl area getting to some wiring bundle/relay/component/????
What do you think? Where do I start? Anything more specific would be appreciated. Thanks!
Noticed sometime after a rain. (both occurrences)
Noticed a very small amount of dirty water on the psgr side floor coming from near the firewall area, I think. Does NOT appear to be coolant.
With the ignition switch in the OFF position, and the AC switch in the AC position, the fan continues to run at very slow speed. When the AC sw is moved to OFF, the uncommanded fan operation stops. (both occurrences)
The check airbag symbol appeared and stayed on steady (both occurrences; it was reset by dealer the first time)
With Ign sw OFF, clicking from under the dash found to be coming from the turn signal relay thing--with ign sw RUN turn signals worked normally with no unusual clicking. (first occurrence only)
Speedometer remains at zero regardless of speed. Odometer doesn't moves either. (second occurrence only)
Windshield wipers intermittently responsive to switch position--no real pattern. Once they got going, they worked OK. (second occurrence only)
Seat belt warning light appeared when it shouldn't have, then went out (second occurrence only)
No other electrical components have displayed problems yet. Engine works normally, idles fine.
What I think....small water leak somewhere in the cowl area getting to some wiring bundle/relay/component/????
What do you think? Where do I start? Anything more specific would be appreciated. Thanks!
#2
10-18-2006, 04:32 PM
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Possible water/coolant infiltration to passenger compartment.
If coolant,should smell like antifreeze. Check the area in front of the windshield for trash buildup(leaves,pinestraw,crud).
Might have a moisture problem with the pcm. Disconnect neg side of battery first, Disconnect each connector from the pcm.Using a GOOD quality spray electronic connector cleaner(CRC),spray each connector on the pcm and wiring harness.Ensure the connectors are dry before reconnecting to pcm. Reconnect neg battery terminal. Hopefully this will resolve your problem.
If coolant,should smell like antifreeze. Check the area in front of the windshield for trash buildup(leaves,pinestraw,crud).
Might have a moisture problem with the pcm. Disconnect neg side of battery first, Disconnect each connector from the pcm.Using a GOOD quality spray electronic connector cleaner(CRC),spray each connector on the pcm and wiring harness.Ensure the connectors are dry before reconnecting to pcm. Reconnect neg battery terminal. Hopefully this will resolve your problem.
#3
10-19-2006, 05:59 AM
I did not think '97s had this problem as well, but it sounds like the windshield is leakng. This happened on some MY trucks, and caused the GEM / Central Junction bos to get soaked, causeing strange things to happen.
The only reason I mention this is due to the water on the floor, and the wipers acting up. The odometer I would have thought to be no op, as a '97 is still the rollign wheel version, but I guess it can have the same problem as the digital odometer.
If you do a search on windshield leak or GEM* you will find several posts on this topic from some time back.
If you can get up behind the dash, position yourself to take a look at the fuse box, and split the GEM from the central fuse box and you will see green fuzzy corrosion between them. Take a read through the thread here, and see if it matches up, prior to taking anything apart. PCM is still on the pass side in '97 I do believe. That is where it was at '01+
This is the best I can see with the symptom list, and the gemlins happening.
The only reason I mention this is due to the water on the floor, and the wipers acting up. The odometer I would have thought to be no op, as a '97 is still the rollign wheel version, but I guess it can have the same problem as the digital odometer.
If you do a search on windshield leak or GEM* you will find several posts on this topic from some time back.
If you can get up behind the dash, position yourself to take a look at the fuse box, and split the GEM from the central fuse box and you will see green fuzzy corrosion between them. Take a read through the thread here, and see if it matches up, prior to taking anything apart. PCM is still on the pass side in '97 I do believe. That is where it was at '01+
This is the best I can see with the symptom list, and the gemlins happening.