Relay Id and electrical Diagnosis Help

I have this posted on comanche club too, but I'm thinking it's not gonna get results as this is on a 92 late xj.

I'm trying to figure out what the relay that goes into the brown receptacle under the dash on a 92xj controls. There is a cluster of three relays on a bracket that attaches to the kick panel on the driverside. With an aftermarket stereo installed and this relay in place the stereo is always on. If I remove the relay the stereo performs as it should. I've double and triple checked the wiring of the radio. searched for any disconnected or obvious ground errors. Any help would be appreciated. I do not have a stock radio to test, but I've used my multi-meter and a test light. The ign wire at the stereo plug is getting power from the relay through the coil or some other back fed item controlled through this relay. If I try to turn on the blower the deck looses power. All these tests with the ignition off.


The pink wire that energizes the coil at this relay(85) has power all the time unless i pull the dome fuse. The other side of the coil (86)at this relay is yellow with a black tracer.




vehicle info:
92 4.0 laredo 4x4

I need to know what this relay controls so I can chase down my short, or just decide if i'm not going to plug it back in. It's the brown recepticle in the cluster of three located under the driverside kick panel.

Cant find an FSM for that year, but looking at a 95 xj, there was a "LCD illumination relay" that made its way to the factory radio. That one has a constant ground and active hot to the coil when the lights were actuated. The relay supplied power to the factory radio LCD / illumination via Fuse 2 (cigar lighter) / Radio through the relays normal closed contacts. When the lights are one, the Normal open contacts close and feed the illum from the dimmer circuit.

So is the radio wired with an aftermarket harness adapter or were the radio wires spliced right into the jeep harness?

If in fact that is the lcd relay, it will not be needed. Just curious if your radio has all three voltage source wires connected 12v constant (sometimes yellow), ign (red) and illum (orange).

What are the wire colors to the 30 and 87 (87a) pins. I looked through a 93 schematic and didn't find that relay anywhere. It may be a dealer add on or maybe just my bad eyes. Maybe I can find it looking for the 30 or 87 wires instead of the dome light (etc.) circuit. Is it possible it is part of the security system?

Just a wild guess but I've had issues with the dome light circuit in the past, some of the wires run under the carpet on the drivers side and are prone to corrode (turn green with white powder) from moisture (and salt) and partially short.

roggom said:

Cant find an FSM for that year, but looking at a 95 xj, there was a "LCD illumination relay" that made its way to the factory radio. That one has a constant ground and active hot to the coil when the lights were actuated. The relay supplied power to the factory radio LCD / illumination via Fuse 2 (cigar lighter) / Radio through the relays normal closed contacts. When the lights are one, the Normal open contacts close and feed the illum from the dimmer circuit.

So is the radio wired with an aftermarket harness adapter or were the radio wires spliced right into the jeep harness?

If in fact that is the lcd relay, it will not be needed. Just curious if your radio has all three voltage source wires connected 12v constant (sometimes yellow), ign (red) and illum (orange).

Click to expand...

It's wired through a harness. Only yellow and red power wires. I used a multi-meter to verify power at harness. The ign wire at the stereo functions correctly with that relay removed. If relay is connected the ign wire will start with a very low voltage then build to 12. If any other accessories (normally on in the acc) are turned on there is not enough current and the stereo will turn off.

8Mud said:

What are the wire colors to the 30 and 87 (87a) pins. I looked through a 93 schematic and didn't find that relay anywhere. It may be a dealer add on or maybe just my bad eyes. Maybe I can find it looking for the 30 or 87 wires instead of the dome light (etc.) circuit. Is it possible it is part of the security system?

Just a wild guess but I've had issues with the dome light circuit in the past, some of the wires run under the carpet on the drivers side and are prone to corrode (turn green with white powder) from moisture (and salt) and partially short.

Click to expand...

We yanked the carpet late last night thinking the same thing, we disconnected the loom that runs under the carpet and the behavior did not disappear. I will get wire colors going to that relay.

I've seen this cluster of three relays in two other cherokees, but have never had this behavior. This Rig did have remote keyless (atleast it has the receiver in the overhead console). We also disconnected that and the compass and behavior still exists if that relay is plugged in.

The wire at 86 could be called a bash but It looks light pink to me.

30 is black and looped from other relays.
87 is blue with a red tracer
87a is solid yellow

Anyone. Someone has to know what this relay controls.