Brake Light/Tail Lights Grounds?

AlfaVerde88 · #1 (**permalink**) 02-16-2007, 07:52 PM

Tonight while draving around town I noticed that when I pressed the brakes I would see my rear Fog Light Swich illuminate. I am suspecting the grounds so I am going to dive into those tomorrow and my question is where are the grounds for the tail lights? I know of the grounds at the front on the cossmember, the front of the block where the battery grounds, and on the back of the engine towards the firewall. Am I missing any? I am going to handle the job with a wire brush and contact cleaner, but is there anything else to look for while I am at the store? I have dielectric grease, but I have heard of contact enhancers like Stabilant 22 etc. Is there anything comaprable availble at the shop, or will I have to order anything worth while?

**Gubi** · #2 (**permalink**) 02-16-2007, 08:57 PM

That's a common problem with the older taillight boards. Probably it is the ground wire connection at the taillight board rather than the ground to the body itself.

The link below is how I fixed it by bypassing the taillight connector. I ended up running completely new, higher gauge ground wires to the common ground under the rear seat (this was probably overkill, but what the hey).

Holy melted taillight board, Batman!

AlfaVerde88 · #3 (**permalink**) 02-16-2007, 09:29 PM

So you had the same problem? I will check that out tomorrow for sure. I would think that you could rig it to work with the stock connecter though. As long as it works I could care less at this point. I had the same problem on my other Milano. So with your new ground the probelms never came back?

**Gubi** · #4 (**permalink**) 02-16-2007, 09:34 PM

Yep, exact same problem: glowing rear fog light button. It would go away temporarily if I cleaned up the connector at the taillight with Stabilant but would always come back.

Since adding the new wire I've had zero problems.

AlfaVerde88 · #5 (**permalink**) 02-16-2007, 09:37 PM

That is great news to hear! Thanks a bunch for that info. I have a roll of 14 gauge do you think that is good? I am not looking at my wiring now so i do not know what the stock gauge is. I may even go through all of the important grounds and upgrade them while I am at it.

**Gubi** · #6 (**permalink**) 02-16-2007, 10:06 PM

I can't remember if the stock was 16 ga or 14 ga. I ran 12 ga, which like I said is almost definitely overkill.

You *might* be able to achieve the same effect by using the existing ground wire and just bypassing the connector. But since I was fixing it anyway I just went ahead and ran the new wires. I didn't like the fact that you could have three +12 wires going in and only one ground wire of the same size coming out.

AlfaVerde88 · #7 (**permalink**) 02-16-2007, 10:34 PM

i will dig into it tomorrow and see if I can tear out the old ground and replace a new one with thicker wire at the connector and run it to the ground under the back seat. If not, I will do it your way. Thanks again for the help. I am sure it has saved me tons of time. Just out of curiosity though, where is the normal ground for the tailights? I have always wondered. And I can find that common ground by lifting the rear seat bench up? where is that one exactly?

**Gubi** · #8 (**permalink**) 02-17-2007, 09:09 AM

I don't remember exactly where the original ground is, sorry. I *think* I remember it being shown in the wiring diagram as being near the driver's seat along the side of the car, but don't quote me on this.

I couldn't find a decent ground point in the trunk (note that this doesn't mean there isn't one...) so I just ran the wires to the ground point I knew of. It's under the rear seat bottom on the driver's side, near the rear window relays and speedo box. Bolt to the body with a bunch of black wires - can't miss it.

The wiring passthrough from the trunk is in the upper corner of the trunk. So you need to remove the rear seatback and trunk trim also, but that's pretty easy.

AlfaVerde88 · #9 (**permalink**) 02-17-2007, 09:32 AM

thanks again! I will get that done today.

AlfaVerde88 · #10 (**permalink**) 02-17-2007, 11:21 PM

fixed! what i did was clean off the boards and bent two tabs for the ground strap on the back of the boards so they were sticking straight out. the tabs i used were the tabs on either side of the board so if there was a bad spot the oter side would compensate. i soldered some 14 gauge wire to each post on spliced them into an eyelet connector and bolted them down to the trunk latch using the two 10mm bolts. one on each side. now, no problems. the only wierd thing is that the rear fog lights are not working now, but i think that the current that was building up in the switch may have burned it out. the front ones work, the relay is good, but the switch is done. i will try to plug it into the other switch or jump the connector to make sure, but other than that everything is working like a champ. i used the Detoxit stuff and it worked pretty well. i hear better things about the Stabilant 22 so i will order some of that next week.

nizam · #11 (**permalink**) 02-17-2007, 11:48 PM

Got pics of your mod?

75evo · #12 (**permalink**) 02-18-2007, 12:06 AM

I think this is a problem with the early type circuit boards. AFAIK there are 2 types of rear tail light circuit board. The earlier ones (like the ones on my '87 Gold) tends to suffer from grounding problem and the plastic conecters tend to melt at one of the connectio points.

AlfaVerde88 · #13 (**permalink**) 02-18-2007, 08:05 AM

i did not know that there were two types. my vrede is an 88. i will take some pics today.

**Gubi** · #14 (**permalink**) 02-18-2007, 08:48 AM

Yep, the photos in the link I posted above show the older style. The newer ones are apparently less problematic.

AlfaVerde88 · #15 (**permalink**) 02-18-2007, 01:25 PM

Here are the pics. I am sorry that one of them is blurry, but I am sure the point will still get across.