Tail light gremlins. Where is the DIC MODULE located?

[Bossman429]

Ok so heres the deal.

My left brake light works intermittently. Sometimes it comes on, sometimes it doesn't. The 3rd and right brake light work fine.

 

So I caught it not working and grabbed a test light. No power at the left socket. No power at the rear tailight harness. The right side is fine though, I used a wiring diagram to figure out which wires should have power and when.

So my next step according to the wiring diagram for the brake lights is to check for power that should be sent to the left, right and 3rd brake lights from the DIC module.

Then check to make sure I am getting power from the brake switch, which I assume I am, because 2/3 of the brake lights work.

I'm sure there is just a shitty connection at the DIC module that is causing it to act up.

 

So I pulled my console top out to get to the DIC screen, and wiring. A group of wires runs from the DIC screen down to the bottom of the console and follows a loom of seat control wire to under the passenger side front seat.

Looking under the seat there is a black box mounted to the floor, and also a tan colored box attached to the under side of the seat. Both have gobs of wires to them.

Sooooo.....is the DIC module the black box mounted to the floor?

According to the Wiring diagram. The wire that carries the left brake signal is a LT BLU/BLK stripe wire. The wire from the DIC M to the right brake light is DK BLU/WHT The wire from the brake switch to the DIC M is light blue, no stripe. All of these wires should plug into, or come out of the DIC Module.

So did I find the DIC module under the seat? I think I did , because the only other thing it could be is ABS module, but I thought that was the box under the radio area. Plus the data wires (DK GRN/WHT. YEL, and RED/WHT) leading from the DIC screen to the mystery box under the seat should be a dead giveaway.

I'll probably pull my seat out later this week, but just wanted to get some valuable info early if possible.

Thanks!

[LukeZ34]

The ABS controller is under the passenger side seat.

The DIC computer (from what I've been told) is under the passenger side dash. If the problem isn't there, then it's probably in your turn signal switch. When those start acting up, they can cause strange problems with the L&R brake lights (excluding the center mount brake light).

The hazard switch in my old Lumina started acting up. I lost both my rear brake lights, but the center one still worked. If I jiggled the hazard switch around I found that the brake lights would flicker on and off. I crammed a piece of folded up paper in it and that worked temporarly, but I eventually had to replace the turn signal switch to fix the problem.

[Bossman429]

Yeah, I thought about the Turn Signal switch, but it is new as of a few months ago, plus jiggling it around doesn't help any.

I might pull the seat out tommorow and see where the data wires from the screen lead to, the HAVE to go to the module.

[Robby1870]

Yeah, I thought about the Turn Signal switch, but it is new as of a few months ago, plus jiggling it around doesn't help any.

I might pull the seat out tommorow and see where the data wires from the screen lead to, the HAVE to go to the module.

 

I have a similar problem with me STE. I do not have ABS, but I have not had either left or right brake lights since I got the car, but the 3rd brake light does work. I replaced the turn signal switch a few months ago and it did not help anything. Im really stumped on this one. Im really thinking about trying to bypass the brake lights going through the signal switch, but I dont know if it will help. If you figure anything out, please let me know, or if I can help in anyway, I'd be glad too, cuz I'd like to have brake lights too.

[Bossman429]

robby, Can I assume you have the DIC with a lamp monitor? Does your DIC indicate a burnt out bulb anywhere?

After studying the wiring diagram for it I think our problem is going to be in the DIC Module circuit, or (hopefully) just wires.

The brake switch sends the brake light power to the DIC through one wire. The DIC is what splits the one 12 volt signal into 3 signals for right, center, and left brakes. This split is also where the comparator measures the resistance in the circuit for the lamp monitor to tell when a light is out. So, I'm guessing our problem stems somewhere within that DIC monitor setup.

My lamp monitor gives no indication of a burnt out bulb, even when that left light is out. If I remove the bulb completely then the DIC will tell me that a TAIL light is out, but seems oblivious to the left brake light not coming on.

I'll have to follow those wires to the DIC module and start sorting through brake light wires.

[Robby1870]

Right now, I have the normal tailights installed on the car (see my sig), so Im using a non STE tailight harness. The DIC tells me the STP lamps are out, the left and right brakes only, not the center one. That is just b/c of the different harness. If I plug the old harness back in, there arent any lights telling me bulbs, I think, I'll have to check that tomorrow.

 

So, you're saying you think the problem is the DIC itself, or the computer for it?

[Bossman429]

Well, when you say DIC do you mean the DIC screen in the console? If so then no.

I believe there is a problem with the DIC module/computer, but I'm going to have to go wire fishing today to see where it is.

According to the wiring diagram it should have a crap load of wires coming in and out of it, almost as many as an ECM.

It's going to be a matter of finding the module, testing for a 12 volt power from the brake switch, then testing for power at the brake light output wires from the module.

If the module is F'ed up, I'm not sure what I'll do, maybe take it out and clean it up, then hope for the best? I dougt GM still carries the DIC module.

[Robby1870]

Well, when you say DIC do you mean the DIC screen in the console? If so then no.

I believe there is a problem with the DIC module/computer, but I'm going to have to go wire fishing today to see where it is.

According to the wiring diagram it should have a crap load of wires coming in and out of it, almost as many as an ECM.

It's going to be a matter of finding the module, testing for a 12 volt power from the brake switch, then testing for power at the brake light output wires from the module.

If the module is F'ed up, I'm not sure what I'll do, maybe take it out and clean it up, then hope for the best? I dougt GM still carries the DIC module.

 

Plus, even if they do carry it, it will cost $Texas

[digitaloutsider]

$Texas

And you wagered.. texas.. with a dollar sign in front of it. Simply amazing..

 

Sorry. Please continue on with your thread.

[GP1138]

$Texas

And you wagered.. texas.. with a dollar sign in front of it. Simply amazing..

 

Sorry. Please continue on with your thread.

 

I was going to say something about that, but I figured I wasn't going to bring it offtopic.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SUCK IT, TREBEK!!!!

[Bossman429]

Uuugggggghhhhhhh!

It's too hot out!

I started to take the interior apart to follow those wires. I got the bolts out of the front seat, then found that I would need a swivel to get the rear bolts out. I didn't have a swivel in my small tool arsenal, so I decided to put it back all together.

I found a bunch of wires along the passenger side door sill, a few of which matched the ones out of the DIC screen.

I suspect that the DIC Module is behind the glove box somewhere.

I will wait until November or December when it is cold outside, and warm in the shop to continue with this project. Cause right now it's hot in the shop, and even hotter outside.

Thanks for chatin with me robby, I'll let you guys know what I find.

If anybody out there has had their DIC stuff out and knows where the module is located, great! Let me know, it might motivate me to go back out and try again.

[Robby1870]

I plugged in the factory STE brake light harness last nite to see if anything changed, and it didnt. The DIC still indicated I have "STP lamp" out and my brake lights dont come on.

[Bossman429]

I was looking at the wiring diagram for the DIC....

The data lines from the compass display unit, and the DIC Module go through connector C200. Isn't that the giant harness that goes through the firewall?

 

Maybe the module I am looking for is under the hood?!

[Robby1870]

Im pretty sure the C200 is the firewall connector.

[LukeZ34]

I always thought the DIC computer was under the passenger side dash.. You know, next to the lock relay, hazard flasher and such.. In that area.

[Bossman429]

I always thought the DIC computer was under the passenger side dash.. You know, next to the lock relay, hazard flasher and such.. In that area.

I looked around in there, but not real close. I did see the convienience center, and the C200 Firwall harness, but not any thing else that was obvious. It was too hot to trace down wires though, so I gave up.

[digitaloutsider]

I almost positive it's under the passenger seat.. (below the carpet)

[Bossman429]

Under the ABS module? or someplace different?

The ABS module is under the pass seat.

The seat control module is under the drivers seat.

I thought it was under the pass seat until I looked it up on AllData (Somedata) and it said the ABS control module is under the pass seat under a plastic cover.