Hey all,

Lately, my battery has been draining completely after leaving the truck sit for a time. Sometimes it drains after just a day. I've bought two batteries already, so I don't think the battery itself the problem. And the batteries recharge once I run them in the vehicle for a few hours so probably not the alternator either. No lights coming from the instrument panel either.

Something is drawing energy from the battery.

Some background...Recently, I had my SLS replaced with Coil springs but I don't know if they disconnected the compressor properly. Definitely, no computers or electronic equipment involved. I was thinking maybe a sensor was telling the compressor to recharge the absent air shocks and the compressor was draining the battery. But I can't hear any sort of motor noise and that should only come on when the door is opened. When I did the coil conversion, I also had some off-road lights installed which I have since disconnected but the battery still drains.

Otherwise, the stereo seems to be shutting down when I turn the ignition off and the interior lights turn themselves off too.

Any ideas on what could be causing my battery to drain or how to figure it out would be much appreciated.

Thanks.

 

Your parts left behind from the SLS system are running when vehicle is off trying to keep it level, etc. The valves and compressor used a common ground line. You'll see that in the RAVE circuits manual. The ground runs to this bolt under the hood, just remove it and tape up. Note - the other earth connection there is for the fuel pump, and if it is left off truck won't crank.

The ground for the valves and pump is C0811.

 

Connect an ammeter in series with the battery. Note the amps drawn and start pulling fuses one at a time until the draw disappears.

 

If the parasitic drain is constant, the ammeter will work, be it clamp on or series style. A normal drain is going to be under 50 milliamps, but that varies with vehicle, lots of clocks, alarms, radio memory, and various CPUs are still using some power. It won't be zero.

If no meter available, a tail light bulb can be rigged in series between battery post and battery cable, it will be bright with a heavy demand. As stated, pull fuses to narrow it down. One guy found the sub amp for rear door was staying powered up, etc.

The valves for the SLS are not constant, but the system cycles during the powered off period to keep vehicle level for the eventual approach by her royal highness.

 

Another thing to check is the alternator, with the ammeter (or light bulb) still connected, disconnect the power lead to the alternator. I've seen where bad diodes in the alternator will cause an excessive parasitic draw.

 

Unplug the SLS compressor, problem solved.

 

Not just the compressor, the SLABS will keep cycling the solenoid valves. Common ground gets them all.

 

Thanks so much for the feedback on the battery drain issue. As recommended, I disconnected the ground from the SLABS and made sure to leave the fuel pump ground attached. I fired the truck up this morning without any problem. It was draining overnight before.

Folks on this forum also correctly diagnosed a bad TPS problem that I had a few months back. Saved me a lot of time and money ...and agony.

This forum is really useful and enjoyable especially for a novice like me.

 

This forum is really useful and enjoyable especially for a novice like me.

Thanks for the feedback.

 

Buzz, in post #2 of this thread you suggest disconnecting the SLS ground as part of trying to reduce parasitic battery drain. I did so yesterday, and after that warning chimes began sounding intermittently when the truck was being driven. (No warning lamps illuminated.) I reconnected the ground and the chimes stopped sounding. That indicates to me that the SLABS ECU is still looking for signals from the SLS system even though the SLS relay (R5) was removed when the air springs were replaced with coils 8 1/2 years ago. I tried to read the circuit diagrams to determine what else could or should be disconnected in the SLABS system to reduce power drain without triggering the chimes but I came up short. Any ideas, please?