Hi All - I've read up a bit on similar but different electrical problems with the 2005 GC's, but still can't fix mine. So it's time to write.

2005 bare bones model Grand Caravan with 340,000 miles; 3.3 engine. When I bought it months ago everything worked. Drove it several days, everything was fine. Let it sit in the driveway a couple weeks. Next time I drove it the gremlins had moved in. First thing I noticed was that the radio was dead. From the time I lost the radio, it acts as follows:

When key is off, the only things that work are the horn, hatchback brake light, and hazards; no power locks, no headlights, no main brake lights, no interior lights.

When the key is turned to accessory, the windows work as they should, as do the main brake lights, interior lights, headlights, and heater blower. Power locks unlock but do not lock. All functions on the key fob quit working at the same time.

With the key in the run position (engine either running or off) all the electricals work as they should except the radio, which remains dead.

When the van is first started, all analog gauges max out for a few seconds, then drift down to zero. Fifteen seconds after starting, all instrument / warning lights come on and then go off in turn. The instrument light cycle seems typical, it just starts late.

The van runs and drives fine.

With the van shut off and key removed from the ignition, the tach stays at last idle speed for 15 seconds, then drops to zero; the heater blower also remains on for approximately 10 to 15 seconds; the digital PRND21 shift indicator and odometer stay lit for around a half minute, and are the last to shut off.

And just to confuse things.... With the key out of the ignition, I can get my locks, headlights, and interior lights to work by running my hazards. Yeah.

The problems are not erratic. They all came at once and are consistent. It seems the default answer for 2005 electrical problems is that the BCM may be bad, but it just doesn't seem like that from what I read of others' problems. I've left the battery disconnected over night, wiggled connections under my battery tray, and wiggled connections on the BCM.

Any help is appreciated greatly. I don't have much hair left to pull out. If I get this one fixed I will post an update for the benefit of the community.

 

First check fuses 19 and 14 in the IPM. Pull them and check for corrosion in the fuse holder. If you see any, you've got the dreaded corroded IPM. If they're good and no corrosion, then you've got either a bad BCM or a shorted module on the data bus. Pretty hard to diagnose without a scan tool. But one way to do it is to get a wiring diagram and start disconnecting all the modules on the data bus. If one of them is shorted out, the data bus will come back up.

I know you're skeptical that it's the BCM, but you should know that the horn, high mount brake light and hazards DON'T run through the BCM. Did that convince you?

 

Number 19 fuse looks good. Number 14 fuse had a corroded blade and some corrosion visible through the side window of the fuse. So it might be corrosion in the fuse mount?

Might not matter, but when the key is off and removed I can get all the gauges and heater blower to shut off by turning my hazards on. Am I feeding power to somewhere through this hazard circuit?

 

I had those kinds of crazy electrical problems on my 01 GC. After some reading on the internet, I pulled the battery and flopped the fuse box over, pulled the connectors and cleaned everything to the best I could. Reassembled... problems changed for the better, but was still not right. Cleaned again - still not right.

After some more searching on the internet, I concluded that the fuse box was the culprit.... couldn't find a replacement in the local junk yards, so I ordered a new one online from a dealer in FL. I put in the new one, all the issues disappeared immediately. Turns out there is a circuit board in the bottom of the fuse box, and it was corroded. Cost of the new box was about $265.

 

Thanks for the response. This thing is crazy. I would guess that there's no way of knowing it's the fuse box without replacing it, right?

 

When it comes to the IPM, as RickMN states on his website, if you see corrosion on the internal circuit boards - replace it. Other than that you can proof the circuits using a multimeter but you'll need factory wiring diagrams to do it. Not a wiz with a meter? Try shake tests. Fire it up and wiggle or tap the IPM and all the wire harnesses and connections while someone sits inside and watches for any changes.

 

Same but different,,,, Battery went dead while van sat for 6 weeks, charged battery enough to start which it did but, next day went to start and nothing no clicking as if low battery, no radio, all else seems to be with power??? Can'nt see leaving a trickle charger on for a day doing damage???

 

I wasn't able to prove it without a doubt. I had similar hazzards related behaviors as well.

Recommend you get the replacement online, I saved $100 that way.

Good luck!

 

Well, I'd been driving the van as it was until tonight. After reading up one more time on similar (but different) problems that others have had over the years, I decided to take the IPM apart. There was a substantial amount of corrosion on the circuit board pins. So much that the fluffy oxide was bridging several pins. One was corroded totally off. I cleaned everything, soldered on a piece of sewing pin to replace the missing pin, hosed everything down with WD-40, and reassembled. The problem is gone. Everything works again.

A half-hearted and temporary fix? Definitely. But remember, I'm over 340,000 miles. The only money I want to put in this thing is for gasoline.

Thanks all for the help. Hope this update aids someone in the future.