Complete Loss of Electrical Power
08-20-2011, 10:42 PM
#1
Nordschleife Master
Thread Starter
Complete Loss of Electrical Power
MY 87 S4 A/T. Car well maintained. Today when turning on light switch, it killed running engine WHILE DRIVING. Afterward car has absolutely no power. No door lights; nothing when turning the ignition. I was traveling in Canada, and am now stuck there. Battery was fully charged (new by 3 months). I have a pigtail and 'trickle' it all the time, even when I travel.
20 mins later the car has power and starts crisply.
I have 300 miles to home. Yes I can travel by daylight.
Had the car towed (1st time and it was sad event), up in a local garage and all connection from battery to starter/alternator looked fine. I just don't get the light switch thing. See my post from July 'Tricky AC problem'. I have light switch issue related to AC relay power cutoff. Now it is killing overall power out of the harness.
Grateful for comments.
Craig
20 mins later the car has power and starts crisply.
I have 300 miles to home. Yes I can travel by daylight.
Had the car towed (1st time and it was sad event), up in a local garage and all connection from battery to starter/alternator looked fine. I just don't get the light switch thing. See my post from July 'Tricky AC problem'. I have light switch issue related to AC relay power cutoff. Now it is killing overall power out of the harness.
Grateful for comments.
Craig
475hp/460lb.ft
08-21-2011, 12:34 AM
#4
Team Owner
^^^^ what Jim said
also open battery compartment and reclean all of the battery connections.
clean the hot post wires and the 14 pin connector above it
also open battery compartment and reclean all of the battery connections.
clean the hot post wires and the 14 pin connector above it
08-21-2011, 01:41 AM
#5
Rennlist Member
Comments? Same advice as last week.
Park the car and go through all electrical connections systematically.
Change the key sensors pre-emptively.
Trace and inspect wires.
Clean ground points / replace ground straps
Clean the 14 pin.
and so on.
You've got to forget about chasing individual circuit issues, thinking that your car has just one one more minor bug to fix.
Your car has what 85% of them have --- the need for immediate and complete electrical review and refresh. Its a little confusing and time consuming, but its relatively inexpensive, satisfying and positive from a safety perspective. And change the fuel lines if you haven't already.
Park the car and go through all electrical connections systematically.
Change the key sensors pre-emptively.
Trace and inspect wires.
Clean ground points / replace ground straps
Clean the 14 pin.
and so on.
You've got to forget about chasing individual circuit issues, thinking that your car has just one one more minor bug to fix.
Your car has what 85% of them have --- the need for immediate and complete electrical review and refresh. Its a little confusing and time consuming, but its relatively inexpensive, satisfying and positive from a safety perspective. And change the fuel lines if you haven't already.
Last edited by Landseer; 08-21-2011 at 02:16 AM.
08-21-2011, 11:29 AM
#6
Nordschleife Master
Thread Starter
I removed the outside alarm system in its entirety. Re did all the wiring splices appropriately and qualitatively. Sleepy Sunday morning here in Canada. Found a nice B&B for my son and I. I'm going over to the local garage in an hour to do a few things.
08-21-2011, 12:09 PM
#7
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Don't turn on your lights anymore. 
Sorry. I hope you figure it out. Definitely drag a comb across the entire car cleaning every electrical contact you can reach, scrub your grounds, replace the block strap and the battery strap, etc.
One time I was driving my 93 Trooper through some heavy rain out in CA desert when I came upon a flooded area. I hit the water, it splashed up onto the alternator (which rides at the very bottom of the engine.....bad place) and it instantly killed the car. It wouldn't restart, hell, wouldn't even crank over. Had it towed to a shop, they removed the battery terminals, scrubbed the **** out of them, scrubbed the battery posts, re-installed, Trooper fired right up and ran great all the way home.
Sorry. I hope you figure it out. Definitely drag a comb across the entire car cleaning every electrical contact you can reach, scrub your grounds, replace the block strap and the battery strap, etc.
One time I was driving my 93 Trooper through some heavy rain out in CA desert when I came upon a flooded area. I hit the water, it splashed up onto the alternator (which rides at the very bottom of the engine.....bad place) and it instantly killed the car. It wouldn't restart, hell, wouldn't even crank over. Had it towed to a shop, they removed the battery terminals, scrubbed the **** out of them, scrubbed the battery posts, re-installed, Trooper fired right up and ran great all the way home.
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08-21-2011, 12:40 PM
#8
Rennlist Member
Could a bad ignition switch cause this? I had something similar happen on my 86.5 and when I slapped the pod it went back to normal. Next time it happened I moved the key around and the issue went away, so I bought a new ignition switch but have not installed it yet. The issue hasn't happened since the new switch arrived, of course.
08-21-2011, 12:47 PM
#9
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Could a bad ignition switch cause this? I had something similar happen on my 86.5 and when I slapped the pod it went back to normal. Next time it happened I moved the key around and the issue went away, so I bought a new ignition switch but have not installed it yet. The issue hasn't happened since the new switch arrived, of course.
How much do you want for the switch?
08-21-2011, 01:40 PM
#10
Electron Wrangler
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The most likely cause is the battery ground strap. Very few oher options allow for the car to lose all power (dead) and yet soon after be alive again... think about this one? Its also a well know failure mechanism...
if you have booster cablles bypass the ground strap with one half and try again...
Alan
if you have booster cablles bypass the ground strap with one half and try again...
Alan
08-21-2011, 09:12 PM
#11
Nordschleife Master
Thread Starter
Alan,
Greetings. One of the first things I checked up top was the ground strap. Fastened tightly to both battery and 'masse punkt' which was recently emory clothed down. Even razor cut the covering off to see if it were severed. It was not. Sparked well with hatch open.
Visited car today and all power on. Car started up briskly. Turned light switch and instant shut down. Restarted and the light switch did it again. Just got hockey bag out to air out gear and now there's no power when hatch opened.
Greetings. One of the first things I checked up top was the ground strap. Fastened tightly to both battery and 'masse punkt' which was recently emory clothed down. Even razor cut the covering off to see if it were severed. It was not. Sparked well with hatch open.
Visited car today and all power on. Car started up briskly. Turned light switch and instant shut down. Restarted and the light switch did it again. Just got hockey bag out to air out gear and now there's no power when hatch opened.
08-21-2011, 10:40 PM
#12
Rennlist Member
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"...all connection from battery to starter/alternator looked fine."
Appearance has little or nothing to do with function in electrical connections. If your main battery connections have not been cleaned, you don't know what you have. It is very possible for there to be a connection that will carry full power one instant and no power the next. Remember that you cannot check this with a voltmeter! Imagine a battery cable that is broken except for one tiny strand of the cable. It will show a full 12 volts, but will pass only fractions of an amp of power.
It is also possible to have a battery that has a broken internal bus bar or cell connector. Same thing - full power one instant, nothing the next.
You need a load tester to have a chance of finding this. You can mcgyver one using a headlamp or headlamp bulb, or a 12 vdc blower motor. See if you can kill the power and start testing at the battery. Test positive post (not terminal) to negative post (not terminal). If you have power, test terminal-to-terminal. If you have power, test positive to body. ETC, ETC. Find where the power disappears.
Appearance has little or nothing to do with function in electrical connections. If your main battery connections have not been cleaned, you don't know what you have. It is very possible for there to be a connection that will carry full power one instant and no power the next. Remember that you cannot check this with a voltmeter! Imagine a battery cable that is broken except for one tiny strand of the cable. It will show a full 12 volts, but will pass only fractions of an amp of power.
It is also possible to have a battery that has a broken internal bus bar or cell connector. Same thing - full power one instant, nothing the next.
You need a load tester to have a chance of finding this. You can mcgyver one using a headlamp or headlamp bulb, or a 12 vdc blower motor. See if you can kill the power and start testing at the battery. Test positive post (not terminal) to negative post (not terminal). If you have power, test terminal-to-terminal. If you have power, test positive to body. ETC, ETC. Find where the power disappears.
08-21-2011, 11:07 PM
#13
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Maybe you can explain the symptoms again... better...
what does no power mean... what is off 0v & what is still on ~12v
Assume dash lights all out.. what else.. is the front jump post @ 0v, what about battery +
Alan
what does no power mean... what is off 0v & what is still on ~12v
Assume dash lights all out.. what else.. is the front jump post @ 0v, what about battery +
Alan
08-22-2011, 12:33 PM
#14
Rennlist Member
[QUOTE=WallyP;8808513 Test positive post (not terminal) to negative post (not terminal). If you have power, test terminal-to-terminal. If you have power, test positive to body. ETC, ETC. Find where the power disappears.[/QUOTE]
Wally: you differentiate between "Post" and "terminal" I'm confused, as I always think of these terms as the same. By "Post" do you mean with no other wires attached or if I'm using a DVM, sticking the probe on the post itself w/o touching any of the collar or wires attached? TIA.
Wally: you differentiate between "Post" and "terminal" I'm confused, as I always think of these terms as the same. By "Post" do you mean with no other wires attached or if I'm using a DVM, sticking the probe on the post itself w/o touching any of the collar or wires attached? TIA.
08-22-2011, 01:01 PM
#15
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The post is part of the battery, the terminal is part of the car. It is common for there to be a problem with the connection between the two.
Yes, use the DVM probes on the battery posts first - what you get is pure battery condition. Then test at the terminals - but go back and read the previous post again about the difference between volts and amps. A voltmeter will NOT always find the problem.
Yes, use the DVM probes on the battery posts first - what you get is pure battery condition. Then test at the terminals - but go back and read the previous post again about the difference between volts and amps. A voltmeter will NOT always find the problem.