Engine/Transmission (1994 - 1998) HELP! what is this ground wire from?

[Garry Verheyden]

I just installed my new 6 spd and started the truck up and my charging system is having a draw on it somewhere. The GEN light comes on in the dash. I drove it for 5 minutes and watched the voltage rapidly drop from 13. 5 volts to about 8. 5-9 volts. I disconnected the battery and the engine shut off right away. I thought it might be my alternator, but the blue wire on the alternator has power on it while the engine is running and after 5 minutes the alternator wires were warm as if it was putting out a lot of power. I then thought the heater grid might be stuck in the on position so I disconnected both the heater grid wires and restarted it. Immediatly after starting, the ground wire on the brake booster caught on fire. I shut the truck down and now am trying to trace back this ground wire and find the problem. What is this ground wire from, and where do you think the draw on my charging system is coming from???

 

[Todd T]

first did you have an auto or manual originally?



have you checked the grounding to the engine block. all the instrumentation and the antilock brakes use a "case" ground so the block needs to be grounded to the frame.



i am trying to find that ground but the diagrams in my manual dont really say where the grounds are connected.

 

[Garry Verheyden]

Todd,

I originally had a 5spd with rear anti lock brakes only. So far I have traced the wire(which is now all burned up) to under the fuse box on the driver fender, but have to remove more components on the fender to firewall to continue my search.

Garry.

 

[HEMI®Dart]

This may not help much but the same wire on my truck (OEM original) is burned and melted too. . I would like to know what it is too.

 

[Howard Durand]

According the manual for my "94", that wire is called the "Brake Ground" and is the grounding source for The fuel tank, vacuum sensor, wiper motor and the underhood lamp.



I have looked through the schematics for the electrical system and it appears all of the grounds are tied together at a single device called a "Ground Joint".

I haven't been able to find out just where this "Ground Joint" is located but I would assume that if the brake ground wire insulation is burning off, it is carrying more ground current than it is designed for. It is only an 18 gauge wire.

I doubt if the ground joint would be the problem unless it has come loose from it's attachment to the vehicle.

More likely, one of the other grounding points has come loose or broken putting excessive current through the 18 gauge wire to the brake grounding point.

The first place I would check is the grounding tie between the engine and the body. Then check all of the grounding screws you can find for good contact or for broken wires.

If you have a service manual it shows where each grounding point is.



Since this started right after changing out transmissions, you should really look over everything that you did to see what could have been changed electrically.

Make sure the grounds from both batteries and the alternator are made up and are tied together.

Also, make sure the positive leads from both batteries are tied together.

 

[Garry Verheyden]

Hemi Dart,

I found the problem, after pulling off lots of wiring armor for a few hours. Howard was right, the ground wire goes under the fuse box on the fender, to the wiring harness along the driver fender. From there, it splits three ways including to a junction with a bunch of ground wires which is attached to the driver fender just behind the fender fuse box.

After tracing many wires, I found that the main wire that goes from the battery positive to the 120A fuse to the wiring harness along the front of the engine was worn through on the shock tower. When this happened, it blew my 120 amp fuse which stopped the alternator from charging my battery. Through my previous tests I thought the grid heater might be stuck on so I disconnected the heater grid wires and started the engine. When I did this, the ground wire caught fire. But now it all makes sense.

When I disconnectd the heater grid wires, I disconnected a very good ground wire as well as a positive wire. Since the alternator was charging and the wire from the alt. goes to the 120A fuse, it was grounding out on the shock tower, therefore energizing my frame. Since the ground wire that burned up is attached to a ground wire on the fender, it ended up continuing the charging fom the frame ground to the ground on the brake booster. The small 18g. wire coudn't take all that power and burned.

Hemi,

Have you ever blown your 120A fuse before or maybe done some welding on your frame? This probably could have been what caused yours to burn. If you have burned a 120 fuse before, maybe you have rubbed your wire through also and it happens to not be touching anymore.

Either way CHECK THE WIRE FROM THE 120 AMP FUSE ALONG YOUR SHOCK TOWER IF IT IS RUBBING ON YOUR SHOCK TOWER IT IS A DEFINITE FIRE HAZARD!!! Sorry for rambling so long.

By the way Howard, thanks for taking the time to look that information up for me.

Garry.

 

[Howard Durand]

Garry,



You did a great job locating the problem. Electricity is neat stuff as long as you can keep it where it belongs.



This forum is a fantastic source of information where we can all help each other.

I'm happy that my comments were helpful. I have certainly learned a lot from others readling through the different threads.



I notice you are the one that has the 47RH for sale. Wish I had the money, I would buy it for a spare.



Howard

 

[illflem]

While on the subject of stray grounds...

Don't know how long you ran it but this may be something to consider. Ph test paper is cheap from a pool or hot tub outfit.



Here's a part of a bulletin I received pertaining to replacing an electrolysis/acid damaged radiator.



Electrolysis



What is it? Chemical change, especially decomposition, produced in an electrolyte by an electric current.



What causes it? Most likely it is caused by improper vehicle grounding. Electrical grounding problems can stem from poor installation of aftermarket accessories or uncorrected vehicle collision damages.



How to detect it? First, test your antifreeze with ph test paper. It should be neutral or some what alkaline. If the coolant has been effected by a stray current it will be acidic. Another way to test would be with a voltage meter to see if there is a difference in the coolant voltage and your vehicle ground.



How do you fix it? 1) You must find and correct the electrical problem (stray current). 2) You will need to completely flush your entire cooling system. Acidic contaminated antifreeze left in the engine block will eventually ruin another radiator. 3) Once the new radiator is installed, you must use only new quality antifreeze and distilled water. Never use recycled antifreeze or tap water. 4) Once everything is installed properly you need to retest the system, insuring the coolant is neutral to alkaline.

 

[HEMI®Dart]

Thanks Gary and you other guys for doing the leg work on this wire. I have never blown the 120A fuse. Never had any welding done on the truck. It didn't rub thru on the shock tower. I think this wire burned after on 2-3 years of owning the truck. It has not been recent. I cleaned up the grounds I could fine in the engine compartment. I will see if it gets hot.

 

[Howard Durand]

Illflem,



I haven't tried any ph paper yet but did a check with the voltmeter

and find that I measure 12. 4 volts with the meter connected across the driver's side battery and am reading 12. 5 volts with the meter connected between the drivers side battery and the radiator coolant.

I think the difference is probably because I am getting the meter probe completely immersed in the coolant providing a little better contact.

Since I have not had any electrical problems, I am assuming this is normal.

 

[Xgunfighter]

You have probubly already checked this but if not, I had the same symptoms you are describing and it was a main fuse from ther alternator. Apparently someone (probubly me) hi the rear of the alternator and blew the fuse. Did exactly what you describe. Not a cheap fuse either. Good luck... ... ... .....

 

[Xgunfighter]

Had the same symptoms myself. Someone hit the alternator rear with a ground and blew the main fuse. Acted just like you are describing. Ran for five to six blocks before volts got down to 8-9. Expoensive fuse... . Good luck. .

 

[Joseph Donnelly]

Here's the fix for hitting the connections on the back of the alternator (all to easy to do when changing the oil filter). Clean the area with electrical contact spray cleaner, blow dry. Squirt on black (to match, or use you favorite color ) RTV filling the recess and covering the contact studs. I did this to mine when new.

 

[Bob4x4]

Another option to protect the alt stud is to use the factory cover off an 02



Bob