Grounding problem
05-22-2013, 06:42 PM
#1
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Car: 1988 Iroc
Engine: 383
Transmission: TH400
Grounding problem
Hi Guys,
I hope someone can help steer me in the right direction with this one. I'm working on a project car and have a problem with the ACC and Tail portion of the fuse box. I'll outline he problem
Using a multimeter and trace signal I am able to tell the ACC fuse and the Tail fuse are grounded out. For example, if I hook one lead to the ground of the chassis then I will read that ground signal on the positive AND negative of the cigarette lighter or other accessories (or at fuse box).
I have disconnected the battery completely and still show ground on both fuses
I have disconnected the c100 and have the ground on both fuses
I have disconnected the cigarette lighter and defroster (same)
I have pulled every fuse out of the fuse box and (same ground problem)
Under the drivers dash there is a heavy purple wire that is also grounded, also the purple wires going in to the back of the fuse box along with the orange wires for the acc are being grounded.
All of the other fuses are not grounding
Here is what I know does not work... Headlights, fog lights, radio, gauge lights, dome light, trunk hatch.
The car does start, crank over, run fine (it was converted to carb so no more tpi, ECM, etc) however it often needs to be jumped as it seems the grounding problem kills the battery over about a day.
Suggestions? Thanks!
I hope someone can help steer me in the right direction with this one. I'm working on a project car and have a problem with the ACC and Tail portion of the fuse box. I'll outline he problem
Using a multimeter and trace signal I am able to tell the ACC fuse and the Tail fuse are grounded out. For example, if I hook one lead to the ground of the chassis then I will read that ground signal on the positive AND negative of the cigarette lighter or other accessories (or at fuse box).
I have disconnected the battery completely and still show ground on both fuses
I have disconnected the c100 and have the ground on both fuses
I have disconnected the cigarette lighter and defroster (same)
I have pulled every fuse out of the fuse box and (same ground problem)
Under the drivers dash there is a heavy purple wire that is also grounded, also the purple wires going in to the back of the fuse box along with the orange wires for the acc are being grounded.
All of the other fuses are not grounding
Here is what I know does not work... Headlights, fog lights, radio, gauge lights, dome light, trunk hatch.
The car does start, crank over, run fine (it was converted to carb so no more tpi, ECM, etc) however it often needs to be jumped as it seems the grounding problem kills the battery over about a day.
Suggestions? Thanks!
05-27-2013, 04:33 PM
#4
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Car: 1988 Iroc
Engine: 383
Transmission: TH400
Re: Grounding problem
I added two pictures (front and rear of the fuse block) and highlighted each spot on the panel block that has ground on it. Anyone know of a circuit that all of these are running in to? or from? I have also disconnected the clip on plugs from the fuse block and still have the c100 disconnected at the firewall. The ground exists when the key is in the run position or in the off position. Also, these measurements were taken with the fuses out as shown in the photos.
At the very least, does someone have an accurate wiring digram of an 88 Iroc? The 89's and 87's I have found do not match up to this.
There has to be one wire or circut thats feeding these, seems like too many to all have ground problems, anyone know which one it is?
images: https://picasaweb.google.com/1041437...eat=directlink
Thanks!
At the very least, does someone have an accurate wiring digram of an 88 Iroc? The 89's and 87's I have found do not match up to this.
There has to be one wire or circut thats feeding these, seems like too many to all have ground problems, anyone know which one it is?
images: https://picasaweb.google.com/1041437...eat=directlink
Thanks!
05-28-2013, 04:14 PM
#5
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
You’re Grounded
Sometimes the under-hood or hatch light does not go out so check those easy ones first.
Then connect an ammeter in series with the battery.
If there is more than 50 milliamps there is excessive draw.
(You can use a small bulb such as a side marker bulb if you don’t have an ammeter.)
Disconnect the alternator wires to see if IT’S the problem.
With everything turned off and doors closed observe the current flow.
Pull the fuses one at a time, including the pump fuse near the battery, till you see the current drop.
That’s the circuit with the problem.
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Happy Racing!
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I Hit The Water Barrels Because My Car Was Dirty
Then connect an ammeter in series with the battery.
If there is more than 50 milliamps there is excessive draw.
(You can use a small bulb such as a side marker bulb if you don’t have an ammeter.)
Disconnect the alternator wires to see if IT’S the problem.
With everything turned off and doors closed observe the current flow.
Pull the fuses one at a time, including the pump fuse near the battery, till you see the current drop.
That’s the circuit with the problem.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Hit The Water Barrels Because My Car Was Dirty
05-28-2013, 09:12 PM
#6
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Car: 1988 Iroc
Engine: 383
Transmission: TH400
Re: You’re Grounded
Hi NINÅ,
Thanks for the response. What I am seeing is not a draw, and I currently have the battery disconnected (both positive and negative) as well as the c100 block so that should eliminate any under the hood wiring. I've checked the alternator wires and they weren't the problem. The problem is that my multimeter gets a ground connection on those fuse points I highlighted. Do you happen to have a schematic for an 88 or know what those circuits may have in common?
Thanks for the response. What I am seeing is not a draw, and I currently have the battery disconnected (both positive and negative) as well as the c100 block so that should eliminate any under the hood wiring. I've checked the alternator wires and they weren't the problem. The problem is that my multimeter gets a ground connection on those fuse points I highlighted. Do you happen to have a schematic for an 88 or know what those circuits may have in common?
06-03-2013, 04:28 PM
#7
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
You’re Grounded
Originally Posted by bourneash
Using a multimeter and trace signal I am able to tell the ACC fuse and the Tail fuse are grounded
If no, then you are implying there is only leakage to ground —— if that’s the case you can still use the ohmmeter to trace wires and find where a connection is where it shouldn’t be.
The ACC fuse and the TAIL fuse are fed from the same fusible link therefore are connected on the + side.
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The headlights don’t even use a fuse therefore the headlight problem can be solved independently.
Using the voltmeter, probe the red wire at the switch.
Is there power there?
If no, probe the fusible link.
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Hopefully someone will be able to post the diagram you have requested, but you should be able to solve the problem without one VIA tracing.
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I Don’t Mind Wreckin’ On The Track, No Paperwork To Fill Out
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06-12-2013, 07:27 PM
#8
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Car: 1988 Iroc
Engine: 383
Transmission: TH400
Re: You’re Grounded
The fuses do not blow, so I have some sort of leakage to ground. I am still unable to find the source, i have been tracing wiring, probing and still at a loss. The weird thing is where I am all seeing the leakage, for example, I am seeing it on the + side of the electric fans. It just doesnt make sense where the leakage is.
06-18-2013, 04:10 PM
#9
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Car: 1988 Iroc
Engine: 383
Transmission: TH400
Re: You’re Grounded
I have been narrowing down the problem and have removed the following wires from the fuse panel. Each one shows a leakage to ground.
From the back of the fuse (power out)
Orange - acc / batt / batt
Pink/black st -gauge
Grey - inst
Also, testing near the battery, the +12 wire going to the started (disconnected from the battery) shows a ground... And the crank wire to the started is showing ground.
Any idea why I would be showing a connection to ground on these?
From the back of the fuse (power out)
Orange - acc / batt / batt
Pink/black st -gauge
Grey - inst
Also, testing near the battery, the +12 wire going to the started (disconnected from the battery) shows a ground... And the crank wire to the started is showing ground.
Any idea why I would be showing a connection to ground on these?
07-01-2013, 05:53 PM
#10
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
You’re Grounded
Originally Posted by bourneash
Any idea why I would be showing a connection to ground on these?
Make sure you are using a low cost analogue meter, not a digital one.
Originally Posted by bourneash
What I am seeing is not a draw……..
Originally Posted by bourneash
……..grounding problem kills the battery over about a day.
Also, if the ACC and TAIL have “leakage to ground” an ammeter in series with those fuses would show a draw.
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Happy Racing!
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My Brakes Don’t Work AT ALL When The Car Is Sliding On It’s Roof
Last edited by NINÅ; 07-01-2013 at 05:58 PM.
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