I installed my new CB the other night with some help from my brother. He found a black wire with white stripes in the fuse box to use as a ground wire, and plugged the live side into an empty fuse slot to draw power. All looked good, and the CB came on no problem, but when we clicked the transmit key, we heard some kind of relay click in the car.

We decided that despite the continuity reading on the multi-meter, what we thought was a ground-wire was not in fact a ground wire. We moved the ground and got no more relay clicks when pushing transmit, so the CB is working fine to all appearances.

BUT, now my service engine light is on... any thoughts? Coincidence? (doesn't seem likely)

Thanks.

Hedron

That doesn't sound good. You need to get the fault cleared by an independent shop.

If that doesn't work, carefully remove the CB, put an innocent look on your face and visit the dealer.

Why dont you figure out where that "ground wire" is going

try to follow it to fuse and away form fuse

or see f some thing dont work
(wipers, horn, radio ... )

FYI - In the Xterra the only wires that can be assumed to be grounds are solid black. Black with a white stripe is just another color and used for many things. To name a few:

Absolute pressure sensor
Washer fluid warning lamp
Throttle position sensor
Crankshaft position sensor
Evaporative system pressure sensor

Here's an update. The light stayed on for a day or two. I then did two things.

First, I tightened the gas cap on the theory that it just MAY have been a coincidence that the cap was loose just when I installed the CB. It sat in the parking lot at work all day, I drove it home (35min drive) and the light still stayed on.

That night I was doing some errands and I decided to unplug the power for the CB from the fuse box. The light stayed on. I shut off the engine and went into a store. I came out, started the car and the light was off.

I plugged the CB back in and turned it on. The light did not come back on, and has not yet come back on since. So perhaps the problem is solved!

Hed

you're lucky - the computer must be satisfied that whatever sensor you disturbed has now been "repaired."

now you know why professional installers have jobs!