Mechanics

BATTERY DRAIN

1999 GMC Jimmy

Electrical problem
1999 GMC Jimmy V6 Four Wheel Drive Automatic 116000 miles

I have recently run into some electrical trouble with my 99 GMC Jimmy. New battery alternator and starter, but still there was trouble starting in the mornings after sitting over night. I've found, by attaching a test light to the negative cable and the negative post to the battery that the RDO/BAT fuse 19 is the culprit, or at least the majority of my drain. Problem is that it controls the speedometer, Tach, Radio, and Heating and cooling. I've had the dash apart and unhooked the radio, hoping it was the main problem but the light seemed to persist, although the test light did fluctuate/pulse with the radio plugged in. Speedometer and tach have acted up before, rapidly jumping and reading the wrong speed, but not for a while. If you have any ideas on what to check I would greatly appreciate it.

thanks
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Jimmrocket3
December 1, 2007.



Similar issue - current battery draw on 99 GMC Jimmy V6 4-W is ~1700 mAmps shortly after removing key; pulling RDO BAT fuse reduces to ~600 mAmps. Removing radio only reduced to ~1100 mAmps. After some extended driving, have seen speedomter bounce around then zero out, but remember tach being okay, but not totally sure. Plan to test more fuses later, since I just learned the actual should be less than 30 mAmps, but any ideas on fixing RDO BAT fuse drain is appreciated.

Tiny
Adahr
Jun 26, 2012.
Need to do a Battery drain test. Do you have a DVOM and a little electical savy?

Docfixit
Jun 26, 2012.
I have a cheap multimeter I set at 10A and test draw across neg bat term to get readings and just basic electrical knowledge. I already ruled out alternator and a bunch of other things via engine fuse box like starter (which sounds like it might be struggling), but didn't check everything. Once I saw ~1100 mAmp drop in drain with 50A INT BAT fuse removed, I moved investigation inside.

I've had battery issues for years, as this vehicle has not been regularly driven since 2006 - mostly used to tow a boat. As such, only after market thing I installed was hitch/power connection, but ruled that out early. However, the dealership installed an alarm system that I did not purchase, so was never turned on, but somehow the system stayed onboard and caused months of headaches ~ 4 years after purchase. Supposedly, they removed everything once I figured out why the car would not randomly start and have not had an issue since.

This car has those full-time running lights that cannot be turned off, but can't find any lights on with engine off - I've even disconnected engine light under hood and turned off interior dome light, to reduce drain.

As for radio drain, the radio did have a couple internal lights (for buttons) that went out a few years ago, but never gave it much thought. However, based on what I'm seeing, I seem to have more problems than just the ~500 mAmp drain with radio disconnected.

Lastly, there is a clicking noise inside vehicle every time I test the drain when checking fuses and understand it might be related to a TBC fuse (?), Which I plan to investigate tonight.

Tiny
Adahr
Jun 26, 2012.
O.K. With 50 amp INT in place after hooking meter up for 30sec what is draw. Then in I/P fuse box removefuse #13 aux pwr does it drop? Repeat for fuse #9 rdo and #7hdlp let me know. Assume no wiring diagram?

Docfixit
Jun 26, 2012.
To clarify, I previously traced the entire power drain from the 50A INT BAT to the interior 10A RDO BAT fuse. However, your 30sec request added new twist to data; No RDO BAT initially tested ~high 0.6 to 0.7, then slowly settled to 0.55A after 30 sec

With RDO BAT, the test initially registered between 1.95-2.0A for ~20 sec, then would drop to 0.55A. I tested this three times and same each time.

After this new data, I guessed this is only a temporary drain and not the long term problem draining my battery dead. So I was going to focus on what was causing the 0.55A drain.

Per an online recommendation, I tried pulling the TBC fuse (Truck Body Computer) and got no reading. Thinking this was odd, I put fuse back in and noticed my tester was going whacky on the 10A setting - numbers bouncing around. The other settings (voltage, ohms, etc) appear to work fine, but figured I must have fried the 10A setting somehow, as there was no spark when contacts touched separate points for negative terminal as before.

If you agree, any ideas how this got fried? Was it testing for full 30 sec or something with the no TBC test or was it b/c it was a cheap unit (~$8) at Wal Mart.

My tester says 10A/15sec max each 15 min, so I began thinking that maybe my tester crapped-out on purpose after ~20sec and gave the lower reading, but since it lined-up perfectly (0.55) wasn't for sure.

What do you think?

Tiny
Adahr
Jun 26, 2012.
Does anyone know how long it is supposed to take for response?

Tiny
Adahr
Jun 28, 2012.
Adahr, we've been having database problems. I just noticed this thread needs attention.

With the engine off, check battery voltage. Then have someone crank the engine and see what the voltage drops to. It should go no lower than 10.0/10.5 volts. Then see what it says with the engine running. It should be at least 13.2-13.8 volts.

Next, you need to take it to a place like Autozone or Advanced and do a 'starter draw test' to see how much current the starter is drawing from the battery.

These tests will give us an idea of what's going on.

Never test a circuit with a multimeter on the 10A setting if you have any reason to believe the circuit has more than 10A running through it. You will fry even a very good meter every time. I've done it a few times. With expensive meters.

Rivermikerat
Jul 29, 2012.
Well, this problem started at Advanced Auto. I had a battery go dead after only a few months and got my one free replacement. They ran the voltage check, but couldn't tell me much. The guy noted that my starter could be going bad, but fairly certain he said that was not my drain problem. Since the battery was dead within two weeks, I took it back for another diagnostic and specifically asked about the starter, but was told it was okay. He said take it to a technician to trace the problem, but figured I could nose around a little myself. The battery is fine if I drive it every day, but dies after only a couple of days sitting, even with the interior 15A RDO BAT fuse pulled.

Tiny
Adahr
Jul 29, 2012.
Hmmmm. Ok. If you remove one of the battery cables, what sort of spark do you get? A little little one, or a substantial one?

Pull fuses in the interior fuse panel one at a time and repeat the battery cable-spark test until you have no spark anymore. At that time you will have found the problem circuit. Then you just need to figure out what the problem is with that circuit.

I would call around and find a reputable shop that will do a battery load test and a starter draw test and a charging system test. They're easy to do, but sometimes the less that stellar intelligences of Autozone and Advanced are incapable of understanding them.

Rivermikerat
Jul 29, 2012.
You're right - at my local place, there used to be at least 1-2 guys who knew their stuff and it was a huge help just to chat with them on auto stuff, but not this current group.

I feel like I'm getting a good spark, so like your spark test idea. The last guy had me hold for 30 sec, which I believe damaged my meter. I'll keep testing and let you know what I find.

Tiny
Adahr
Jul 29, 2012.
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