Electrical Gremlins
05-09-2003, 05:57 PM
#1
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Electrical Gremlins
I've got an '86 944 that's suffering from some electrical problems. The windsheild wipers, windows, and climate control are all on the fritz. They were working fine until a few days ago when all three systems died simultaneously.
Obviously, I've checked the fuses and relays, but since all three stopped at the same time, and are independent of one another, I don't think the problem is this simple.
Are there any other common points to these three systems that could fail and take them down? Thanks in advance.
Obviously, I've checked the fuses and relays, but since all three stopped at the same time, and are independent of one another, I don't think the problem is this simple.
Are there any other common points to these three systems that could fail and take them down? Thanks in advance.
05-09-2003, 06:59 PM
#3
Big thirst, Sore Thumbs
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Napoleon
Er ahhhhh
Also pull the steering wheel and check the contacts there.
More I think abuot it grounds though. Maybe someone who has more knowledge of late wiring will know a central point.
Also pull the steering wheel and check the contacts there.
More I think abuot it grounds though. Maybe someone who has more knowledge of late wiring will know a central point.
05-10-2003, 12:41 AM
#4
Burning Brakes
Sid is right (I keep saying that don't I?)
'grounds is grounds' on the late P-cars too
your need to 'tune-up' some connections...first disconnect the negative terminal cable from the battery so you can work safely
just like the earlys...look for several brown wires screwed to the chassis...there are something like 7 to 9 locations
for your problem, very suspect would be the few ground points under the dash
get confortable under there
start on the left side of dash...a couple of ground points close to the underside of the fuse/relay box...then go to the right side
the procedure is to undo the nut...take sandpaper to the copper wire ends and make them shiny... then get dielectrict 'tune-up' grease (from a auto parts store) and coat the copper ends to keep them from oxidizing again and improving conductivity...screw it all back tight
besides the (3?) ground points under the dash there are others up front on either side of the engine down low on the chassis (what would be the 'frame' if it wasn't a unibody)...also by the brake lights, hidden by carpeting
take the individual wires off the positive battery terminal too...get them all shiny & give them a coating of 'tune up' grease...do both the battery posts and terminals too
follow the negative cable from the battery and clean them where they are connected to the chassis
the starter motor is another great place to clean up the wires...the alternator connects here and then to the battery...don't miss it
you can do all the relay plugs (one at a time) with the tune-up grease...and the fuses...they are all connections that with time get oxidized and begin to behave funny
reconnect the negative terminal cable to the battery...do this again in 2015
if this exercise doesn't fix your problem it will prevent some in the future and it only cost a few bucks for the grease...next place to suspect would be the ignition switch
'grounds is grounds' on the late P-cars too
your need to 'tune-up' some connections...first disconnect the negative terminal cable from the battery so you can work safely
just like the earlys...look for several brown wires screwed to the chassis...there are something like 7 to 9 locations
for your problem, very suspect would be the few ground points under the dash
get confortable under there
start on the left side of dash...a couple of ground points close to the underside of the fuse/relay box...then go to the right side
the procedure is to undo the nut...take sandpaper to the copper wire ends and make them shiny... then get dielectrict 'tune-up' grease (from a auto parts store) and coat the copper ends to keep them from oxidizing again and improving conductivity...screw it all back tight
besides the (3?) ground points under the dash there are others up front on either side of the engine down low on the chassis (what would be the 'frame' if it wasn't a unibody)...also by the brake lights, hidden by carpeting
take the individual wires off the positive battery terminal too...get them all shiny & give them a coating of 'tune up' grease...do both the battery posts and terminals too
follow the negative cable from the battery and clean them where they are connected to the chassis
the starter motor is another great place to clean up the wires...the alternator connects here and then to the battery...don't miss it
you can do all the relay plugs (one at a time) with the tune-up grease...and the fuses...they are all connections that with time get oxidized and begin to behave funny
reconnect the negative terminal cable to the battery...do this again in 2015
if this exercise doesn't fix your problem it will prevent some in the future and it only cost a few bucks for the grease...next place to suspect would be the ignition switch
05-10-2003, 04:52 AM
#5
Nordschleife Master
When my ol' 944 had a problem with the wipers and stuff, there was a short under the dash in the wiring harness; replaced the harness, everything was fine.
Now tonight on my new 944, we found a bizarre, new problem that has been fixed; I noticed that the starter wire was too long, and nearly dragging on the ground. So we undid it, and ran it correctly back through the wall, rather than over it, into the battery area. While in there, Frank jiggled the positive cable, and everything went off. I had the engine running, it just stopped.
So we took the positive cable apart, and what we found I could see from 4' away - green corrosion! So we kept digging into the wire, until we found no more corrosion - went about 3 - 4" down the wire. Stripped, reconnected, no more stalling.
Good luck!
- Julie
Now tonight on my new 944, we found a bizarre, new problem that has been fixed; I noticed that the starter wire was too long, and nearly dragging on the ground. So we undid it, and ran it correctly back through the wall, rather than over it, into the battery area. While in there, Frank jiggled the positive cable, and everything went off. I had the engine running, it just stopped.
So we took the positive cable apart, and what we found I could see from 4' away - green corrosion! So we kept digging into the wire, until we found no more corrosion - went about 3 - 4" down the wire. Stripped, reconnected, no more stalling.
Good luck!
- Julie
05-10-2003, 05:06 AM
#6
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I just learned a hard lesson about bad connections, high resistance and wiring that gets real hot, fortunatly not a lot of $, but jiggling wires doesn't fix the problem......
Tornados have moved on, time to go to bed.
Tornados have moved on, time to go to bed.
05-10-2003, 11:20 AM
#7
Burning Brakes
"Hunter S. Thompson, explaining late night automatic weapon fire" ...wasn't he a reporter for Rolling Stone...who Doonesbury's doped-out 'Duke' was a modeled after? is he still alive?
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05-10-2003, 11:58 AM
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There is only one Hunter S. Thompson, he just wrote a weird biography (where the quote came from) "Kingdom of Fear".
Talk about a warped dude with an interesting (to read about) life.
Talk about a warped dude with an interesting (to read about) life.
05-10-2003, 02:22 PM
#9
Burning Brakes
knew a SF nut that R&R'd in Bangkok with HST...he was in his Gonzo Letters...had an 'import/export' business (gold for guns in Rhodesia)..nutz, both of them, but interesting
05-12-2003, 07:34 PM
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Ok. I've checked all the grounds. Cleaned and greased. Nice low resistivity along all the connections. Checked the ignition switch to the degree possible and it looks good.
But, still no go on any of the systems. I'm starting to wonder if all the relays have gone simultaneously. Is there anyway I could check if the relays are working, given that I have a basic home shop? Or does that take specialized equiptment?
But, still no go on any of the systems. I'm starting to wonder if all the relays have gone simultaneously. Is there anyway I could check if the relays are working, given that I have a basic home shop? Or does that take specialized equiptment?
05-13-2003, 01:21 AM
#11
Burning Brakes
I know you said you checked the relays, but...
do you have +12v on G14(relay x)socket term 30?
when G14 relay contacts close the +12v from 30 should go out to G14 relay socket term 87 and supply the fresh air blower; flasher; window control; coolent fan relays (4 relays) in addition to the windshield wiper motor.
pull relay & make a wire jumper to connect 30 to 87 & bypass relay. could be, dunno
do you have +12v on G14(relay x)socket term 30?
when G14 relay contacts close the +12v from 30 should go out to G14 relay socket term 87 and supply the fresh air blower; flasher; window control; coolent fan relays (4 relays) in addition to the windshield wiper motor.
pull relay & make a wire jumper to connect 30 to 87 & bypass relay. could be, dunno
05-13-2003, 11:45 AM
#13
Three Wheelin'
I agree, the problem could be Relay X (G14), or the ignition switch. Relay X provides +12 v power to bus KL. X in the fuse panel whenever the ignition switch is turned on (accessory or on, first or second position.) Bus KL. X provides switched power to the relays Tom mentioned. If you jump Relay X from 30 to 87, you bypass both the relay and the ignition switch and your accessories should work at all times. Assuming this works, you have narrowed it down.
The next check would be to see if it is the relay or the ignition switch. With Relay X removed, check to see if you get +12 V at terminal 86 when the ignition is turned on. If you do, the problem is Relay X (try swapping it out with your friend's "parts car".) If you don't get power at terminal 86, the problem is probably in your ignition switch.
Let us know what happens.
The next check would be to see if it is the relay or the ignition switch. With Relay X removed, check to see if you get +12 V at terminal 86 when the ignition is turned on. If you do, the problem is Relay X (try swapping it out with your friend's "parts car".) If you don't get power at terminal 86, the problem is probably in your ignition switch.
Let us know what happens.
05-13-2003, 02:48 PM
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Thank you. Thank you. Thank you.
That was it. Manually switched the G14 relay and everything works again. Tore it apart looking for the failure point and could find a thing. No burn marks. No scorching. Nothing. But slip in a new one and everything works again.
Annoying gripe, however. I had a mechanic friend pull the electrical diagrams off alldata.com for me so I could trace the circuits. None of them showed any of these systems being routed through G14. Not sure why, but I wouldn't have found the failure without you guys. Thanks a ton.
That was it. Manually switched the G14 relay and everything works again. Tore it apart looking for the failure point and could find a thing. No burn marks. No scorching. Nothing. But slip in a new one and everything works again.
Annoying gripe, however. I had a mechanic friend pull the electrical diagrams off alldata.com for me so I could trace the circuits. None of them showed any of these systems being routed through G14. Not sure why, but I wouldn't have found the failure without you guys. Thanks a ton.