88 Dodge Xplorer Electrical Problem

[Xplorer88]

I recently got a Dodge 1988 Xplorer 228, low miles very clean. After it sat for a couple of days I found that both the vehicle and coach batteries were dead! Installed new batteries. Problem continued, installed new converter, coach battery stays up OK now. Vehicle battery goes dead in 4 or 5 days. If I'm plugged into shore power, vehicle battery goes dead in 3 or 4 hours! Had to jump the vehicle battery from the coach batter to get going the other day. Anyone have any suggestions on what's killing the vehicle battery? Does anyone have a source for the coach wiring schmatic?

Thanks,

Xplorer88

[g1g]

First thing is to disconnect your batterycable then put a multimeter (set on amps) in line between the cable and battery post. Note the reading then start pulling fuses while checking what the reading is. On the fuse that makes the reading drop most likely has the short. Check with the owners manuel and see what is on that circuit and you may be able to find your problem.

[Mike]

I'll assume you've checked all lights (sure they're off when the van sits idle, and not drawing current), and CO/propane detectors, and any other 12V accessories, and disabled them by disconnecting their wiring or using a coach battery disable/disconnect switch if one exists? I'm guessing (because I'm not familiar with the Xplorer wiring and equipment) that the battery isolator/separator is wired wrong, or has a failed diode or two. Do you know where it is, and can you get a wiring diagram for it from somewhere, maybe from the manufacturer, or online? If you can find a procedure, test it for proper directional flow, and make sure it is inhibiting and allowing flow in the correct directions. It sounds like the coach accessories and appliances/lights (12V draw) are pulling down the engine battery. You might also check with a multimeter whether all batteries are getting 14.4 V when the engine is running (verify the alternator is charging everything).
I had a failed isolator, bad diode, and it would pull down the engine battery when the van sat idle with the coach batteries enabled for a few days. Replaced the isolator, problem solved.

[Xplorer88]

Thanks for the advice from G1G and Mike. Testing revealed a short on fuse #8 which powers the rear window heater. The heater is not used in the Xplorer so that is a prime suspect. I had replaced the batteries and the battery isolation modual, the lead from the alternator goes to one terminal and the feed to the vehicle battery from another, the third lead supplies the coach battery, I will recheck these for correctness. Thanks again and I will report the outcome after I check all of this out.

Xplorer88

[lundsby1979]

I realize this is an old thread, but did you ever find out what caused the short? And did you find out what is running on the circuit from the rear window heater?

I have an '86 Xplorer that I just put on the road. The dashboard light for the window heater came on for a few seconds yesterday, flickered a bit and then went off. It happened a couple of times and has been off since. I'm concerned there may be a short somewhere but haven't found out what made the light turn on.

/Morten