97 K2500 Not Shifting, Odd Electrical Issues

carl s. · May 11, 2009

My 97 K2500 (6.5 diesel) has been having some odd problems lately. A few weeks ago I went to pick up a trailer from a friend. The car drove fine on the way over. On the way back as we got onto the freeway we found it was not shifting out of 1st. Even manually shifting into 2nd or 3rd would not do anything. We hit the hazards to limp on the shoulder to the next exit - when the hazards were turned on, the gauge cluster flipped out. the tach and speedo bounced around, the gauge lights flickered and the engine actually started to run rough.

We pulled off into a gas station and checked the trans fluid - it was full. we pulled the combination meter relay and the hazards fuse. We also unplugged the trailer connection. After all that the truck still would not shift out of first.

The next thing we tried was driving it in reverse, putting it into 4H and 4L which didn't do anything. The last thing we tried was turning the truck off and on. Of course it wouldn't start. absolutely nothing, not even a click. There was a weird buzzing sound, like the door chime module or seatbelt module wasn't getting full power. but that was it.

We then disconnected the battery, and clipped the wires for the electronic brake controller (which is what we were suspicious of due to its poor installation and the fact that the trailer had electronic brakes and the problem only happened once the trailer was connected). Once this was done the truck fired right up and shifted fine. It worked perfectly for the next week (although I didn't really drive it during that period - just once out about 40 miles to pick up another trailer, see below).

Then this weekend I went to pick up a different trailer (drove fine on the way out). About 20 mins of driving with that trailer the problem came back. The first clue was the tach was bouncing and settling on 0 rpm's while driving. then it stopped shifting again. We pulled over, found some wiring left over from the brake controller, removed it and it seemed to be ok. A little later the problem came back but this time the truck got stuck in 2nd instead of first. We parked and messed around with the wiring for a long time. When we started it, it ran fine and shifted fine - we hadn't really changed anything. We drove some more but then the problem came back, we were about 4 miles from a parts store so we limped it along - as we got closer the car lost more and more power and the gauge lights got very dim - almost like a dying alternator. we pulled the alt in the parking lot and had it tested - it was fine. we tried starting it again and it drove fine, shifted and everything - the only thing was we were missing the gauge cluster lights.

Thats where it is now. It seems like it must be a grounding issue to me but any ideas are appreciated.

-Carl

bill190 · May 11, 2009

Sounds to me like the alternator is not charging the battery sometimes and you are running off of the battery.

Then the battery drains and things stop working.

Then you lessen the electrical load by disconnecting something.

Then it works again because less of a load on the battery.

Then battery continues to drain and problem reappears.

Get a battery charger and charge the battery. See if the problems go away for awhile, then reappear. If yes, you are doing the job of the alternator -> charging the battery and it is holding its charge!

So if that is the case, I would suspect the alternator or its associated wiring including ground wires from the battery to the engine.

Auto store testing of alternators does not find all problems with alternators. A good test would be to run the alternator at a fast speed like in the vehicle. Do they do this?

carl s. · May 11, 2009

Sounds to me like the alternator is not charging the battery sometimes and you are running off of the battery.

Then the battery drains and things stop working.

Then you lessen the electrical load by disconnecting something.

Then it works again because less of a load on the battery.

Then battery continues to drain and problem reappears.

Get a battery charger and charge the battery. See if the problems go away for awhile, then reappear. If yes, you are doing the job of the alternator -> charging the battery and it is holding its charge!

So if that is the case, I would suspect the alternator or its associated wiring including ground wires from the battery to the engine.

Auto store testing of alternators does not find all problems with alternators. A good test would be to run the alternator at a fast speed like in the vehicle. Do they do this?

When they tested the alt they spun it up pretty high - not sure exactly what rpm's it went to though. It passed multiple times. It does have a bit of bearing noise

I'm not entirely convinced it's a dying alt - draining battery issue. When we pulled into the parts store the truck was mimicking that problem with the dimming lights, loss of power and then dying but we were able to fire it back up on the first crank after having the alt tested - if it had been running off battery and the battery had drained out it wouldn't have started again, right?

I tried starting it 2 nights ago - it cranked and fired (I don't think I let the glow plugs warm up long enough for it to actually start, didn't have the gauge cluster in). the next time I tried it just made the clicking sound with the weird buzzing noise from somewhere under the dash

edit - I'll try charging the batt to see if it will start consistently

Draenor · May 11, 2009

Since you say its only happening with a trailer connected. I'd start with the wiring for that first(specifically the brake controller). The short is pulling a load on the electrical system, which is why it is appearing that the cluster,lights, etc are going out or crazy.

carl s. · May 11, 2009

Since you say its only happening with a trailer connected. I'd start with the wiring for that first(specifically the brake controller). The short is pulling a load on the electrical system, which is why it is appearing that the cluster,lights, etc are going out or crazy.

well I don't drive the truck to say that definitively. This is a tow rig only - I use it to haul my racecar around. Other than using it to haul the past 2 weekends I haven't driven it. But you're right, it looks like it's related to plugging in the trailer - the truck drives fine on the way out to get the trailer and then the problem appears shortly after plugging the trailer in. simply unplugging the trailer doesn't eliminate the problem. the brake controller was removed the first time the problem arose but there may be some wires from the install still floating around (it was installed very poorly with those stupid vampire type splice connections - there might be more that I haven't found that are partially cutting the wire).

bill190 · May 11, 2009

...if it had been running off battery and the battery had drained out it wouldn't have started again, right?

Actually, if you let a car battery sit, sometimes it will bring its charge up a bit. But there is a limit to this. This is a chemical thing...

http://hyperphysics.phy-astr.gsu.edu/Hbase...c/leadacid.html

Anyway the test is to charge the battery, then see if it runs fine for a while (including trailer lights) then the battery drains down again.

If you have a voltmeter/multimeter, you can check the voltage on the battery before starting the engine. It should be 12 something volts. Then after starting the engine, the voltage on the battery should go up (alternator charging the battery).

carl s. · May 11, 2009

...if it had been running off battery and the battery had drained out it wouldn't have started again, right?

Actually, if you let a car battery sit, sometimes it will bring its charge up a bit. But there is a limit to this. This is a chemical thing...

http://hyperphysics.phy-astr.gsu.edu/Hbase...c/leadacid.html

Anyway the test is to charge the battery, then see if it runs fine for a while (including trailer lights) then the battery drains down again.

If you have a voltmeter/multimeter, you can check the voltage on the battery before starting the engine. It should be 12 something volts. Then after starting the engine, the voltage on the battery should go up (alternator charging the battery).

I'll give that a try tonight (although I'm still going to go through the wiring harness as we've already found one ground wire with the insulation burned off - i think it goes to the blower motor but haven't gotten that far in my investigation)

bill190 · May 12, 2009

...we've already found one ground wire with the insulation burned off...

That does not sound good. I would track that down and find the source of the problem.

carl s. · May 12, 2009

...we've already found one ground wire with the insulation burned off...

That does not sound good. I would track that down and find the source of the problem.

yea i'll take a pic of it tomorrow. we removed the dash so we could get to all the wiring, plugged everything back in and that's about it - battery was at just over 12V when I probed it afterwork, after messing with it and turning the key on several times it was around 11.5V. I'm going to charge it tomorrow but after finding the one burned wire I'm wondering if the wiring harness is fried somewhere else that isn't visible.

bill190 · May 12, 2009

That sounds like fun! (removing the dash )

What worries me about a ground wire burnt would be if it was taking the load from a larger ground wire somewhere (which should have been taking the load).

Ground wires go all over the place and I would guess there could be multiple "paths" for the ground current to travel. So say a large ground wire to the body had a poor connection, it is possible the smaller ground wires could "take up the slack", but this might overload them.

Bottom line, check the larger ground wires (battery to body/engine) to be sure they are OK with good connections.

Also if you have not owned this vehicle since it was new, someone may have shorted something while doing some wiring work and that is all there is to the problem.

Anyway if there is a problem which you have not found, electrical things have a habit of continuing to have problems, so I'm sure you would know about it!

carl s. · May 14, 2009

one of the batteries seemed to be dead so we replaced both (both were of the same vintage so I'm sure the other wasn't far behind). we drove the truck for about 1 hour tonight without incident but have yet to plug in a trailer to test it. hopefully tomorrow night