Sparks and Smoke from above steering wheel, now no "Wait" or "Brake" Indicator

[dherman304]

Well, finally got all of the chores done on HMMWV went to take it for a test drive and accidentally ran over my hi-lift jack, I put it in drive to move over the jack but I heard sparks and looked forward to see sparks and smoke coming from somewhere behind the "dash" (seemed to be coming from above and a little left of the steering column). I turned the truck off waited of the smoke to clear and tried to start it to find no "Wait" or "Brake" indicator working, and it didnt try to turn over. All other lights seem to work in the truck (gauge cluster etc.)

I took everthing off the dash and cant find any obvious signs of a short. I have +24v coming into and leaving the ignition. I checked the 14B wire going into the Smart Box and it has continutity with the ignition wire (when in nuetral).

There could be damage inside the box but that doesnt explain why I saw sparks behind the dash. If it was from the smart box I would have expected the sparks to be more in the footwell.

I know troubleshooting electrical problems is nearly impossible over the internet but Im hoping that someone knows about a wire or somewthing in that area I cant see that could be causing this issue.

 

[Mogman]

Have you removed and inspected the inside EESS box connector and wire connections? make sure to disconnect the batteries first.

 

[dherman304]

Have you removed and inspected the inside EESS box connector and wire connections? make sure to disconnect the batteries first.

Yup. Actually surprised how clean the connections looks.

 

[NDT]

Did the jack pop up under the truck and contact the starter motor causing the fireworks?

 

[Mogman]

If you have run power to the inst. through CB2 then the wire #29C should be hot to the EESS box which should give you a wait light.
You can jump S and T at the diag port just to see if the starter activates.
If you cannot find any other sign of burnt wires etc. you may need to remove the strain relief from the body connector to see if there is any wire to connector problems

 

[mgFray]

Under the dash, just above the steering wheel shaft is a bundle of wires. On my rig that bundle was too close to the steering wheel shaft, it chafed and welded itself to the steering shaft when I was making corner. But if it hadn't done that and then broken there would have been a LOT of heat and maybe smoke. Check your wiring harness for breaks, damager, melting, etc. (In my case, I had to redo the harness due to about 6 or so wires that were badly damaged from rubbing on the steering shaft.)

 

[dherman304]

Did the jack pop up under the truck and contact the starter motor causing the fireworks?

no it just lifted the tire up, and bend the jack pretty good!

 

[mgFray]

This is what I found above the steering wheel shaft. All due to chafing.

 

[dherman304]

View attachment 929260

This is what I found above the steering wheel shaft. All due to chafing.

seems like all of those wires are hard to access. How did you get them so loose?

 

[Mogman]

Here is the schematic for your R1

 

[dherman304]

If you have run power to the inst. through CB2 then the wire #29C should be hot to the EESS box which should give you a wait light.
You can jump S and T at the diag port just to see if the starter activates.
If you cannot find any other sign of burnt wires etc. you may need to remove the strain relief from the body connector to see if there is any wire to connector problems

Thank you so much for the better diagram. I cannot for the life of me find a STI/ICE pin diagram. Is it the same as the 4l80 diagnostic port layout?

 

[Mogman]

Thank you so much for the better diagram. I cannot for the life of me find a STI/ICE pin diagram. Is it the same as the 4l80 diagnostic port layout?View attachment 929286

I am pretty sure that would be a no, can't you see the letters? Maybe someone has the pin out as I don't see one right off

 

[dherman304]

This is what I found above the steering wheel shaft. All due to chafing.

You were exactly right! the steering knuckle was rubbing the main wire loom over the steering shaft. Not only did I find a random broken ground (Not part of the main ground harness) but I saw the webbing around the loom was broken. I used my video scope to get closer and bingo damaged wires and welded globs.

I am pretty sure that would be a no, can't you see the letters? Maybe someone has the pin out as I don't see one right off

I am an idiot, ha! I knew the letters would be small but I still didnt see them the first time. I see them now!

 

[mgFray]

seems like all of those wires are hard to access. How did you get them so loose?

remove the gauge panel. Unbolt the steering wheel, steering wheel brackets, you can hang the brackets down and not have to disconnect the shaft. Then trace the wires unhook them and bring them out under the dash or out of the gauge cluster opening to work on it. Space really wasn’t bad in my case.

 

[mgFray]

After repairing this is what I ended up with. I zip tied the loom to it won’t rub in the future.

 

[dherman304]

Found 2 wires completely destroyed and nearly welded together. one was a 27 wire heading to Smart Box. Fixed the two wires and she fired right up! Im really surprised this isnt a more common issue?

 

[Mogman]

Glad you got her going!

 

[kurtvk]

Here is the schematic for your R1

WOW thas a crisp Wiring diagram, all he ones i have are kinda blurry at he end of he TM's...... Do you have one for the M1123/M1097A2 also ?

 

[FlameRed]

@Mogman I got to ask if you also have a clear copy of the wiring diagram for the M998? I have never seen such a clear copy! That would be awesome!

 

[Mogman]

@Mogman I got to ask if you also have a clear copy of the wiring diagram for the M998? I have never seen such a clear copy! That would be awesome!