electrical issue with 78 928
11-02-2007, 07:35 PM
#1
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electrical issue with 78 928
ok i have this prob with my car ive had for going on two years and when i first got it, it started and of coarse ran like a champ. well now that i moved and finally got it out of the wet climate it was in it has a issue with starting. i replaced the altenator cause it was charging fine but as soon as id shut the car off it would decharge the battery. ok that said ive replaced the stater and a new battery, checked and cleaned my grounds but when i was cleaning the fuse panel i checked with a test light and i have like 10 fuses that there are constant power going to even with the key off. now is this normal or is this a stuck relay. any ideas would be appreciated. 
11-02-2007, 08:02 PM
#2
Nordschleife Master
alot of the fuses will have power the whole time,
what you need to do is get a fluke meter with a clamp,
put the clamp over the wire and it will tell you how many amps are being pulled from the battery.
there should be almost none
what you need to do is get a fluke meter with a clamp,
put the clamp over the wire and it will tell you how many amps are being pulled from the battery.
there should be almost none
11-02-2007, 11:17 PM
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well ill see if i can get my hands on a fluke meter, and the it very well could be the ignition im calling 928intl tomorrow to get one coming. it turns everything on but wont start the car the tumblers are so bad. so i have a momentary switch to start it temporarily. thanks for the suggestions. ill post more as this project continues.
11-03-2007, 02:45 AM
#6
Burning Brakes
Ever had the door panels off?
I remember a stubborn battery drain problem that I worked on with a friends car. Turned out he had just had bodywork done from a door accident and the guys put the wires on backwards to his courtesy lamps in the door. This was the source of his battery drain (believe it or not!)
Cheers
Bernie
I remember a stubborn battery drain problem that I worked on with a friends car. Turned out he had just had bodywork done from a door accident and the guys put the wires on backwards to his courtesy lamps in the door. This was the source of his battery drain (believe it or not!)
Cheers
Bernie
11-03-2007, 03:42 AM
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i have had the panels off and being i have to get new switches and door speakers i tape all of the ends of the wires so they wouldn't ground out. but the thing im curious about is how do i get to the door pin buttons. one of the previous owners either broke or disconnected them cause they are not in the holes anymore im thinking that maybe where my drain is. but i will work on it more tomorrow. slow process but eliminating one thing at a time. once again thanks for the input. 
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11-03-2007, 04:45 AM
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i have had the panels off and being i have to get new switches and door speakers i tape all of the ends of the wires so they wouldn't ground out. but the thing im curious about is how do i get to the door pin buttons. one of the previous owners either broke or disconnected them cause they are not in the holes anymore im thinking that maybe where my drain is. but i will work on it more tomorrow. slow process but eliminating one thing at a time. once again thanks for the input.
https://rennlist.com/forums/928-forum/382491-door-pin-switch.html
11-03-2007, 01:13 PM
#9
Electron Wrangler
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Tazz the fuse situation is probably quite normal many fuses get direct power and are switched after this in various ways (relays, switches).
You can measure the total current in the battery ground strap - you can use a regular DC ammeter (DMM) for this as long as it has a 10A range and you just check for leakage (e.g. don't turn the ignition on).
Try to make sure somehow that the interior lights stay off.
what current do you get? - progressively pull the fuses one by 1 and note the effect on current. After you find the contributors make sure the results are repeatable by trying dfferent sequences.
How much do you have with all the fuses removed?
Your goal is about 25mA or less - 50mA or less would also be manageable (just)...
Report on what you have...
Alan
You can measure the total current in the battery ground strap - you can use a regular DC ammeter (DMM) for this as long as it has a 10A range and you just check for leakage (e.g. don't turn the ignition on).
Try to make sure somehow that the interior lights stay off.
what current do you get? - progressively pull the fuses one by 1 and note the effect on current. After you find the contributors make sure the results are repeatable by trying dfferent sequences.
How much do you have with all the fuses removed?
Your goal is about 25mA or less - 50mA or less would also be manageable (just)...
Report on what you have...
Alan
11-03-2007, 01:46 PM
#10
The 78 model doesn't have lights in the doors so I wouldn't tear the door panel off yet. Another way to check for parasitic draw is to feel the relays when the car hasn't been run for a while. Any sticking relay will feel hot/warm to the touch.
Dennis
Dennis
11-04-2007, 12:21 PM
#11
Dennis,
We'll have none of those easy diagnostic/fixes here on the Renn.
One more Violation and I'll have to report you.
Related issue...
Snuck Pattycakes thruanother inspection. She was having a bad wire day.
Apply the brakes (only when engine is running) and the front right marker illuminates ...dimmly.
Turn the right turn signal on and Viola! The right rear brake light faintly blinks.
I swear!
Pattycakes is like being married to a drop-dead georgeous woman, witth chronic flirtation issues.
We'll have none of those easy diagnostic/fixes here on the Renn.
One more Violation and I'll have to report you.
Related issue...
Snuck Pattycakes thruanother inspection. She was having a bad wire day.
Apply the brakes (only when engine is running) and the front right marker illuminates ...dimmly.
Turn the right turn signal on and Viola! The right rear brake light faintly blinks.
I swear!
Pattycakes is like being married to a drop-dead georgeous woman, witth chronic flirtation issues.
11-04-2007, 01:12 PM
#12
John,
The only area in common for those (side marker and brake) lights is the lamp control unit. May want to check it for moisture, corrosion of grounds or frayed wires. The turn signal and brake lights also share a common ground so there could be feedback voltage if any corrosion. Since corrosion of grounds could affect both situations, that would be my first check. Yep I think Pattycakes needs grounded.
Dennis
The only area in common for those (side marker and brake) lights is the lamp control unit. May want to check it for moisture, corrosion of grounds or frayed wires. The turn signal and brake lights also share a common ground so there could be feedback voltage if any corrosion. Since corrosion of grounds could affect both situations, that would be my first check. Yep I think Pattycakes needs grounded.
Dennis
11-05-2007, 08:30 PM
#13
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well after going through everything i think it is my ignition switch, cause as i said i have a momentary switch to start my car and if i hit the switch before i turn on the ignition it tries to fire right up. and if i turn on the key before that it just clicks at me. so 928 is sending me one hopefully thats the prob.
