Mechanics

DEAD SHORT ON IOD CIRCUIT

1994 Chrysler Town and Country

Electrical problem
1994 Chrysler Town and Country 6 cyl Front Wheel Drive Automatic 215000 miles

I have tried to replace the IOD fuse after losing interior lights and digital dash.

The replacement fuse pops immediately upon insertion, even when the engine and ignition are not " on".

I checked with a VTVM, and found a direct short through the IOD fuse circuit, allowing over 25 amps to pass through the fuse socket, thus burning out the 15 amp fuse in that position.

Do you know what could be pulling so many amps through this circuit? My ohm meter says that there is a direct short (showing full continuity) between the fuse position and the battery's negative terminal.

This tells me that something is direct shorted somewhere in the system that is powered through the IOD fuse. I understand that the BCM is powered through the IOD fuse, and thus when the IOD fuse blows, various electrical systems within the van lose power. My dash is out. The radio is out. Driver's door lock works, but unlocks doesn't. Interior lights are out but cig lighter still has power as does heater fan. Any ideas for me, please?
I'd be happy to offer a fee if someone can give me an authoritative answer and solution to this issue.

I am also considering whether the BCM itself could possibly be shorted internally, but I do not know where the actual BCM is located on this vehicle.
Avatar
EBradley2
March 22, 2010.




Hi EB, first of all, instead of popping a bunch of fuses, use a pair of wires to connect a 12 volt light bulb to the socket terminals. Don't let it touch any plastic trim panels because it will be full bightness and hot. When the short is gone, the bulb will go dim or out.

Start by opening and closing the doors. If you see a change in the bulb, look at the wires in the rubber tube between the hinges. Try twisting the tube.

The under hood light is on that circuit too. If the wire is mispositioned, it can rub through on the sharp edge of the inner fender by the hood hinge, but that will usually pop the fuse when opening or closing the hood.

Besides the things you already mentioned, look at the wires coming through the sun visor arms, the bulb in the ash tray, the glove box light, and the overhead console lights.

You can try unplugging the Body Computer but I'd be surprised if that's what's shorted. Remove the knee blocker under the steering column, then the computer is slid in to the right. Also, on the left side of the dash is a gray 16 pin connector. If the short is gone when you unplug it, look at those wires between the hinges. A wire in there feeds the power mirror switch and the power lock switch.

That circuit also goes to the instrument cluster and the headlight switch.

Caradiodoc

Caradiodoc
Mar 23, 2010.
Hi Caradiodoc!
Thanks for the advise. I connected a 12v circuit testing light toi the IOD fuse position as you suggested, and of course, it lights bright.

I opened and closed all the doors - no change.
I removed the dash, including instrument panel, lights controller pod and right hand pod - no change.
I wiggled all the cabling behind the dash - no change.
I disconnected the BCM completely - no change.
I pulled all the relays behind the center console hatch - no change.
I pulled all the relays behind the driver's knee panel on the left - no change.
I have an aftermarket remote start, doors and hatch popper - disconnected the internal fuses on the unit - no change.

I can't think of what could be providing a direct ground to the IOD circuit. The ignition is off. No accessories are on. And all the fuses in the main fuse block beneath the steering wheel have been pulled. Still. Direct to ground short through the IOD circuit.

Where else does it possible find a ground?

Super strange! At least I found out that pulling the connectors off the BCM didn; t take the short away, suggesting that it's NOT the BCM that's shorting the circuit!

Your thoughts?

Thank you for your continued inspiration!

Edward
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EBradley2
Mar 24, 2010.
Did you find and unplug the gray 16-pin connector on the left side of the dash?

Caradiodoc

Caradiodoc
Mar 24, 2010.

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