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Discussion Starter #1
This is really a two part question.

I fried something that feeds the gauge cluster.

On the L body vehicles the wires from the engine harness that feed into the Bulkhead Disconnect on the firewall how are the wires attached to the bulkhead disconnect? I need to check the red wire for the ammeter at the disconnect but there is a rubber grommet around it that keeps me from reaching the probe into it.

I messed up and blew out the circuit that feeds the gauge cluster. I did check the wire at the bulkhead disconnect for the Tachometer and that circuit was showing about 10 volts and the voltage changed with the speed of the Engine.

No fuses are blown but I suspect I blew out something between the alternator and the gauge cluster. Any idea what I might have fried?
 

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If you still have the fuseable links on the side of the drivers shock tower, it's always good to check there first. Whenone of those blows, the wire will discolor a bit but will feel like a rubber band when you tug on it because the wire inside has vaporized/is gone. You can buy replacement fuseable links at the auto parts store. It's not a real servicable area but you can get down in that area sometimes taking off the clutch cable bracket on the shock tower can help.

The bulkhead connector is held in place with a single bolt in the middle on the engine side of the firewall.
 

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Discussion Starter #3
The one large wire into 4 fuseable links is still there. But as you mentioned you have to remove a bunch of stuff to be able to work with it. Looks like I will have to cut or remove some wire ties and unwrap the wires to be able to inspect it.

The last fuseable link that I had blow was on a 1978 Chrysler New Yorker. Most of the link just melted visibly off the harness. After I replaced it never blew again.
 

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this is really a two part question.

I fried something that feeds the gauge cluster.

On the l body vehicles the wires from the engine harness that feed into the bulkhead disconnect on the firewall how are the wires attached to the bulkhead disconnect? I need to check the red wire for the ammeter at the disconnect but there is a rubber grommet around it that keeps me from reaching the probe into it.

I messed up and blew out the circuit that feeds the gauge cluster. I did check the wire at the bulkhead disconnect for the tachometer and that circuit was showing about 10 volts and the voltage changed with the speed of the engine.

No fuses are blown but i suspect i blew out something between the alternator and the gauge cluster. Any idea what i might have fried?
fusable link
 

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Discussion Starter #5
The Fusable links didn't seem to be bad. I tested the two circuit board connectors. The round gray connector and the straight blue connector. The gray connector terminal "C" for the Tachometer had voltage. The blue connector terminal "3" for voltmeter feed didn't have a voltage reading or show an ohm reading when I hooked the meter to a ground and the "3" terminal.
 

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If you find you have to get into the BH connector, you will find a central bolt that holds the 2, (1/2's) together.

Once you separate the 1/2's, there are master keys that hold the individual wire locks that hold the individual wires in place.

This is a 3 step process to get to the terminals inside the BH connector.

Good Luck
 

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Discussion Starter #7
Ok thanks. I just wish that the last owner didn't feel the need to re-engineer the electrical system and the vacuum system.
 

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Discussion Starter #8 (Edited)
Of course the Bulkhead Disconnect would loosen but it would not separate. I put it back together. Hopefully it was lined up properly and I didn't horribly smash and bend anything.

I did pull a newer L Body harness out of my junk box. I am going to follow the wires to see if I can determine the path of the wire I am concerned about.

D'oh, I swore I checked all fuses twice. I traced the wire on the harness and it went directly to the fuse block. When I checked the fuses I found a blown fuse. Next time I will check them with my meter.

I also found FLASHER, Hazard Warning was bad. I must have blown it out when the fuse blew.

The crazy thing is now the Tachometer is working somewhat where it wasn't working before.
 

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Of course the Bulkhead Disconnect would loosen but it would not separate. I put it back together. Hopefully it was lined up properly and I didn't horribly smash and bend anything.

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The BH connector won't just fall apart into your hands, you have to pull pretty hard sometimes---

Also

Sometimes after you think the bolt is loose, you will pull & pull, then loosen the bolt some more.

Good Luck
 

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Discussion Starter #10
The bolt couldn't get any looser than it was. The main problem was no room to pull on the connector while you turn the bolt.

The problem ended up being a bad fuse. Not sure how I missed the fuse. Only 5 amp so the element is pretty thin.

But the new problem is; "why is the tachometer suddenly working"? Not accurately but at least it responds to the throttle. My best guess is either one of the connections I pulled apart under the hood or the female terminals for the fuse had corrosion on them.

Now I need to get some more DeoxIT to clean the fuse contacts.
 

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The bolt couldn't get any looser than it was.
The main problem was no room to pull on the connector while you turn the bolt.


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I thought exactly the same thing several times....
Apparently the bolt re-tightens a little while you are pulling. I am not saying it is your problem, only that it has been my problem several times in the past.


It fits going together and coming apart.

Again,
Good Luck
 
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