1990 Jaguar Sovereign : No Tail Lights or Parking Lights

For the past few weeks, the tail lights and parking lights on my 1990 Jaguar Sovereign have not been working. I had checked the fuses but found nothing burned out. I had swapped relays from the parts car without success. I even gave in and asked a mechanic to look it over yesterday but after a half hour there was still no success. Even the Jaguar Forums didn’t have the answer. But today, thank God, I found the problem and fixed it!

At work, I had access to the wiring diagram from AllData and found that two related relays might have something to do with the problem. Not only were the tail lights/parking lights not working, but the radio had lost all power as well. Hmm… what was the connection? The two relays at the bottom of the diagram were (1) Radio Lighting Relay, and (2) Auxiliary Side Light Relay. Monday night even the janitor got involved offering the idea that a radio wire might be grounding out the system. That got me thinking. A mechanic had recently replaced the ground wire. Perhaps something had become dislodged in the mean time.

This morning, I looked at the radio wiring and found that the previous owner had done a cheap install of it. Many of the wires had only been wound together and covered with electrical tape. Yikes! As you can imagine, several of the wires had become disconnected and probably had something to do with the problems listed above. Thankfully, I had a box of blue butt connectors and was able to make better connections. Not only does the radio work fine but now all the speakers work.

Later in the afternoon, I got to thinking about the wiring diagram and the lights not working. I had already checked the fuses several weeks ago, so I pulled the panel underneath the passenger side dashboard (below the glove box) and took a look at the relays again. The first step was to replace the Auxiliary Side Light Relay. The original HELLA 12V relay was part # 4RA 003 510-33. NAPA had one for about $7 (Echlin part # AR294). But after replacing the relay, nothing had changed. So, I went back to the electrical diagram.

Notice the squiggly arrow above the second relay? I am not an electrician at all, but I could see that the symbol matched something that looked like a two wire fuseable link hanging below a nearby relay. I looked closer and found that each relay had a “squiggly” attached to it. I still don’t know what that is, but I snipped the old one out and replaced it with one from the parts car. But when I reattached the battery’s negative cable there was an unexpected spark because I had left the headlight switch in the on position. Oops. To be sure, I removed the fuse door on the passenger side and the 4th fuse (3 Amp) on the 3rd column had burned out. That was the one for the parking lights. Once it was replaced the lights worked again! Whether it was the “squiggly” or fuse I’ll never know, but the lights work and I can drive at night again. And that is a wonderful thing.