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914World.com _ 914World Garage _ electrical woes
Posted by: Mike1981 Aug 19 2017, 12:03 PM
Hello everyone
Hoping to get some electrical help on my 72
It has a V8 in it but will not pass any power
No buzzing of the fuelpump
No dash lights
No radio
no horn
nothing
I pulled the ignition switch and tested it
It was open until I turned the key and ohmed to almost 0 ohms
When I released it open circuit
Checked all wires in harness good
Ohmed out every fuse in the panel below dash as well as a few in the rear of the car.
Checked the ground strap (now a battery Cable)
At first I was not getting continuity between the tranny bolt and the body
Cleaned up the connection to the tranny as well as to the body ohms out to 2 ohms
Checked the battery 12.5 volts
Ohmed from neg terminal to chassis ground ohmed to 2-3 ohms
It was running fine yesterday until i turned on the headlights while staring it
then it died and I havent been able to get it to crank
Any help would be appreciated
thanks
MIke
Posted by: Spoke Aug 19 2017, 12:22 PM
Do the lights come on with ignition off?
Do you have any electrical power on anything?
How about the 4-way flashers? They work with or without key in.
Did you clean the battery terminals?
How about the ground strap from battery negative to ground? Is it tight?
What is the battery voltage from positive terminal to chassis ground (not batt neg)?
Posted by: Mike1981 Aug 19 2017, 02:17 PM
QUOTE(Spoke @ Aug 19 2017, 02:22 PM)
Do the lights come on with ignition off?
Do you have any electrical power on anything?
How about the 4-way flashers? They work with or without key in.
Did you clean the battery terminals?
How about the ground strap from battery negative to ground? Is it tight?
What is the battery voltage from positive terminal to chassis ground (not batt neg)?
No lights at all
No power at all
4-way flashers do not work
re-cleaned battery terminals tight
battery neg to chassis ground 12.3 volts
re tightened ground strap to chassis and tranny
no power on fusebox under dash
3 vdc when key is off
0vdc when key is on
thanks for your help
Posted by: Spoke Aug 19 2017, 02:27 PM
QUOTE(Mike1981 @ Aug 19 2017, 04:17 PM)
battery neg to chassis ground 12.3 volts
You mean battery POS to ground?
If battery NEG to chassis ground then there is no connection between battery NEG and chassis. What condition is the negative cable between battery and the chassis bolt above the battery?
If nothing works, then it's likely the battery or wiring, not your ignition switch or the engine ground strap.
Try this test:
Turn lights or 4-ways on.
Measure voltage across the TERMINALS of the battery, not the clamps. Touch the battery terminals.
Then measure voltage from POS terminal to POS battery clamp.
Then measure voltage from NEG terminal to NEG battery clamp.
Here we're trying to find where the battery voltage starts and where it ends since it's not making it to any components.
Posted by: Mike1981 Aug 19 2017, 02:58 PM
QUOTE(Spoke @ Aug 19 2017, 04:27 PM)
QUOTE(Mike1981 @ Aug 19 2017, 04:17 PM)
battery neg to chassis ground 12.3 volts
You mean battery POS to ground?
If battery NEG to chassis ground then there is no connection between battery NEG and chassis. What condition is the negative cable between battery and the chassis bolt above the battery?
If nothing works, then it's likely the battery or wiring, not your ignition switch or the engine ground strap.
Try this test:
Turn lights or 4-ways on.
Measure voltage across the TERMINALS of the battery, not the clamps. Touch the battery terminals.
Then measure voltage from POS terminal to POS battery clamp.
Then measure voltage from NEG terminal to NEG battery clamp.
Here we're trying to find where the battery voltage starts and where it ends since it's not making it to any components.
Yes you are correct
Positive teminal to chassis is 12.3 volts
I turned on 4-ways
No lights as before
0 volts bet pos terminal to pos clamp
0 volts from neg terminal to neg clamp
Posted by: Spoke Aug 19 2017, 03:16 PM
OK, sounds like the battery terminals are tight.
No voltage at the fuse panel? The first 3 fuses from the center of the car outward are constant 12V. If not 12V, then some wiring issue is at play.
How do the small wires look coming off the POS terminal? These wires go to the fuse panel.
Before you go behind the fuse panel, disconnect the battery NEG terminal. Do NOT move the fuse panel with battery connected.
Behind the fuse panel is a POS terminal block on the side of the chassis. Make sure this is tight.
With the fuse panel down, make sure no connections touch anything. Connect NEG terminal to battery. Test the positive terminal block behind the fuse panel from terminal block to chassis. Should be 12V.
Posted by: 76-914 Aug 19 2017, 03:24 PM
Do you still have the OEM positive clamp w/ 3-4 ~10ga wires and a large 2ga cable to starter. IIRC, one of those wires goes to the fuse panel and the other to the ignition switch. Find that wire and check it. If you do have 12v then put some load on it and see if you lose the 12v. I've had some bad connections give me a good reading until they get a little load on them.
Posted by: Mike1981 Aug 19 2017, 03:35 PM
QUOTE(Spoke @ Aug 19 2017, 05:16 PM)
OK, sounds like the battery terminals are tight.
No voltage at the fuse panel? The first 3 fuses from the center of the car outward are constant 12V. If not 12V, then some wiring issue is at play.
How do the small wires look coming off the POS terminal? These wires go to the fuse panel.
Before you go behind the fuse panel, disconnect the battery NEG terminal. Do NOT move the fuse panel with battery connected.
Behind the fuse panel is a POS terminal block on the side of the chassis. Make sure this is tight.
With the fuse panel down, make sure no connections touch anything. Connect NEG terminal to battery. Test the positive terminal block behind the fuse panel from terminal block to chassis. Should be 12V.
Thanks
I will re-check the smaller wires coming off the POS terminal at the battery.
I will then disconnect the NEG terminal and drop the fuse panel and make the check you recommend
thanks for your help.
Mike
Posted by: Mike1981 Aug 19 2017, 03:36 PM
QUOTE(76-914 @ Aug 19 2017, 05:24 PM)
Do you still have the OEM positive clamp w/ 3-4 ~10ga wires and a large 2ga cable to starter. IIRC, one of those wires goes to the fuse panel and the other to the ignition switch. Find that wire and check it. If you do have 12v then put some load on it and see if you lose the 12v. I've had some bad connections give me a good reading until they get a little load on them.
I have some really heavy gauge wires going back to the starter
I put my pos terminal from my multi meter onto the pos on the starter and sparks flew.
I will send a pic of what I have
thanks
Mike
Posted by: Mike Bellis Aug 19 2017, 04:29 PM
Sounds like 2 of the 4 wires connected to the positive battery terminal are disconnected. 2 go to the alternator circuit and 2 go to the fuse panel/ignition switch.
Posted by: Mike1981 Aug 19 2017, 07:18 PM
QUOTE(Mike Bellis @ Aug 19 2017, 06:29 PM)
Sounds like 2 of the 4 wires connected to the positive battery terminal are disconnected. 2 go to the alternator circuit and 2 go to the fuse panel/ignition switch.
I think you may be onto something
i will trace 4 wires back and make sure the connections are tight
Posted by: Mike1981 Aug 22 2017, 01:15 PM
Hello Everyone
Thanks for all the help.
I pulled the NEG off the battery and dropped the fuse panel
Behind it was a terminal block with the positive lead attached just as I was told.
I only measured 3.2 VDC when the key was off and 0 when it was on.
Puzzled I once again checked the fuses this time in the back of the car.
I found 1 fuse that was a 30 amp.
It tested good but was melted.
I had to pull it out with pliers and thus destroyed it.
Went to the auto parts store and picked up a new fuse.
Took some emery paper to the contacts.
Plugged her in and what do you know I have power and she is running again!
You are the most helpful group of folks I know.
Thanks very much!
Mike
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