1996 850W LED third brakelight retrofit wiring question Topic is solved

Post by **boerence** » 03 Nov 2015, 22:15

Hi, Due to driving habits beyond my control (daughter) I replaced the tail gate on a 1996 850 Wagon with one from a 1998 V70XC. The V70 tailgate has an LED third brakelight vs. the standard bulb on the 850. The V70 LED light had 2 wires coming out of it (a thicker pink and red one and a thinner green and yellow one), whereas the 850 had only one (Pink/Red, if I remember correctly). I just cut the wires off of the LED (two-wire plug connector) and spliced the single-wire plug connector on to it.

The light works fine, but every time the brakes are applied the 'bulb-out' indicator on the dashboard lights up. Should I ground the green/yellow wire or something? I can handle mechanical issues pretty well, but I'm not much for wiring diagrams. I tried searching the internet for an answer but came up completely empty.

Just wondering if anyone has any advice or experience with this. It's not a big deal, but dash lights bug me.

Thanks in advance.

Post by **Ozark Lee** » 03 Nov 2015, 22:26

The LEDs use less current than the incandescent lamps that the failure monitor module was designed for so the monitor senses that a lamp is burned out. I think the 70 series module has the same plug and pinouts but it was calibrated for the LED third brake light. I haven't looked at them side by side but my bet is that they could be swapped and get rid of the warning light if you could scare one up at a pick-n-pull.

...Lee

Post by **boerence** » 03 Nov 2015, 22:40

Thanks for the reply Ozark Lee - that makes sense. I'll try to get my hands on one - wish I would have grabbed the one out of the donor car!

I believe the module is located on the right side in the back, if I remember correctly.

I wonder what the green and yellow wire was for...

Post by **Ozark Lee** » 04 Nov 2015, 16:45

The monitor module is in a cavity under the carpet on the left hand (US driver's side) of the car next to the spare tire cavity. Typically it is a blue box that is typically about 3" x 5" and a bit over an inch thick. It has a connector with a dozen wires or so going to it.

...Lee

Post by **boerence** » 31 Dec 2015, 12:17

Hi, just an update on the LED third brakelight question. I made it to a U-Pull and for five bucks got the lamp controller from a 1998 V70 and switched it with the one in the 850, and it worked like a charm! The one in the 850 was blue and the one in the V70 was gray. Thanks to everyone for your help, I REALLY appreciate it!

Post by **BEJinFbk** » 31 Dec 2015, 13:22

Great follow up and the picture says it all.
Thanks for closing the loop on this!

Post by **rspi** » 31 Dec 2015, 14:08

I've been thinking about making that upgrade.

Post by **erikv11** » 31 Dec 2015, 17:00

Thank you for the follow up and the picture, this is great to have documented.