1996 6.5 Turbo Diesel Electrical Gremlin has me stumped

[toadfist]

I have a 1996 Chevy C1500 with a 6.5 Turbo Diesel in it. Everything was running fine until I accidentally ran down the batteries.

After recharging it, it spazzed out blinking all of the dash lights sequentially except the wait to to start glow plug light when you turn the key to run the beeping beeps with the gauge lights flashing. Trying to start just rapid clicked.

I did some research and it looked to me that it was probably a grounding issue. Instead of looking for crusty grounding straps, I ran a 4 gauge welding cable to a freshly drilled hole on the firewall, to a fresh mounting hole on the driver's side fender. I used that mounting point to run 4 gauge welding cable to the frame, and to the battery. Both batteries ground directly to the block with 2 gauge. The passenger side battery grounds to the fender as well. I had the wire, and the hydraulic crimped, and I just wanted to be 1000% certain I had good ground.

I have not made any changes to the truck before this problem, it has been driving great for 6 months.

Unfortunately I didn't film the blinking before I added the grounds. The spazzing slowed down, I guess? It's still messed up. I'm stumped.

Here's a video of the current problem.

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Mods I have done that worked fine for the last 6 months.

Vacuum pump delete
Egr delete, plugged and manifold swapped
Turbo spring added, calibrated with added boost gauge
Aftermarket air intake
2 gauge power to starter, alternator, fuse box connecting both batteries.
Currently the tune is stock.

Also, I know I need to fuse my power cables, I'm doing that once I get this running again.

I am stuck and not sure how to proceed. Any advice would be appreciated... Also if anyone knows a gmt400 diesel wizard near Atlanta, that would also be useful.

 

[RichLo]

Are you sure the batteries are charged? How do you have them wired together? Just positive to positive or do you have an isolation relay or switch to keep them from discharging each other?

 

[toadfist]

Are you sure the batteries are charged? How do you have them wired together? Just positive to positive or do you have an isolation relay or switch to keep them from discharging each other?

The batteries are wired in parallel. I have a bus bar on each side of the bay for positive. Both batteries positives connect to the bus bar on its respective side. 2awg connects both bus bars running over the fan shroud. I get 12.9v probing strait to the battery terminals on both batteries. I get 12.9v going from the left positive bus bar to the right negative battery terminal, and vice versa. 0v probing the positive cable that connects the 2 bus bars, so both batteries are equal voltage, I think... Using a fluke 117.

 

[toadfist]

Decided I woul disconnecy the batterys and voltage test that. Looks like one is head. How embarrassing.

 

[toadfist]

Put in a new battery and confirmed. Thanks guys.

 

[1998_K1500_Sub]

Sorry to hear of your issues.

This highlights for others the value that a DVM and some careful measurements can make in terms of time and effort saved.

That's not to say I haven't spent days chasing the wrong problem. Ask me about the timing chain I once replaced that was totally unnecessary.