Rick's Free Auto Repair Advice

Tail lights don’t work Caravan

Diagnose and fix a tail lights don’t work Caravan issue

Check tail light bulbs first

If you have a mid-2000 or later model, troubleshooting a tail lights don’t work Caravan issue can be mighty frustrating. Always start by checking for power to the tail lights on the white/brown wire. Remove the bulb sockets and use your voltmeter to check for power when the parking/tail light switch is activate. If you don’t have power, move to the next step. Then check for good ground on the black/dark green wire

How tail lights work on Chrysler products

In the old days, power to the tail lights ran through the headlight/park/tail light switch. NOT ANYMORE! On newer computerized vehicles the headlight/park/tail light switch acts as a signal to a computer called a body control module. The module then sends a DIGITAL signal to another device that actually switches power to the light sockets.

tail lights work

Wiring diagram Caravan tail lights

Check the tail light fuses

The tail lights are fused by fuses 2 & 3 in the integrated power module (IPM) located in the engine compartment (or consult your owner’s manual for the right fuse numbers).

Test tail light switch

The multifunction switch turns on the headlights and tail lights. The headlight/tail light portion of the switch only has two wires; white/yellow called Headlight MUX and a white brown wire called Headlamp MUX return. Both wires are connected to the body control module (BCM). The headlight switch has a series of resistors that alter the return voltage back to the BCM. When the BCM detects a voltage corresponding to a driver request for TAIL lights, it sends a digital signal to the integrated power module (IPM) located in the engine compartment. To test the MFS, you’ll need a shop manual with the different voltage values for each setting. The MFS rarely causes a Tail lights don’t work Caravan problem.

At the IPM the digital signal is deciphered and commands the front control module (FCM) to switch ground to the control coil side of the PARK lamp relay. Once ground is provided by the FCM, the park relay contacts close and provide power to fuses 2 & 3. From there, power flows to the parking lights.

Test the park light relay

The easiest way to test the park light relay is to find another relay in the IPM that’s the same size and swap it in. If the tail lights work, just buy a new relay. If they don’t work, you’ll have to test the terminals in the relay socket. With the relay out, check for battery voltage on socket terminals 85 and 30. Then check for switched ground at terminal 85 when you turn the parking lights on. If you see battery voltage and switched ground, the relay and FCM are good and the fuses are good, you’re at the end of the line. From this point on you’ll need a scan tool.

Cause of Tail lights don’t work Caravan

You’re not going to like this, but Chrysler is known for having problems with the IPM. That shouldn’t have been a surprise to anyone with any brains. You don’t put a computerized circuit board and relays under the hood in an enclosed that’s not waterproof. If you confirm that the BCM is getting a park light request and the request is being sent to the IPM but the IPM doesn’t switch on the parking lights, you’ll probably need a new IPM. Prepare to dig deep.

©, 2017 Rick Muscoplat

Posted on by Rick Muscoplat


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