CC149

I finally got around to installing my last gauge, the fuel pressure one. After I restarted the truck it did not work. I thought maybe the ground I chose was not good enough. So I removed a screw (with the truck running) on the drivers side fender that had a black wire with a brown tracer and grounded the sending unit there. The wire goes into the main harnes. The gauge works fine but now the abs and brake light are on.

Anyone have a wiring diagram handy to tell me what that wire is for? I did remove the fuse taps and run the sending unit wire through the firewall while doing this job. I did look at the parking brake light switch wire and it seems to still be hooked up. My brake lights still work.

Could this just be coincidence and the abs sender in the differential just went at the same time? Or could I have set a code by unhooking that ground wire with the engine running? Could I have disturbed something else during the install?

I know, I know, I should not have unhooked that wire with the engine running. Do you have to use a scanner to try and reset the light?

Sorry so many questions.

ps I read through 16 pages doing the search thing but found nothing close to this.

Jim

97 2500 stick, rear wheel only abs, 4wd

mishkaya

Don't know much about this stuff, but did you check your fuses and relays? You never know...
mishkaya

wcbcruzer

You know... On my last truck which was a '95 Cummins, once I pulled the wire harness out of the brake master cylinder/ABS and after I plugged it back in, both my ABS and brake light were on. It wasn't on before. So I unplugged it again, blew air through it, plugged it back in and fiddled with it a little and both lights went off again without ever coming back on. NOBODY would've ever been able to troubleshoot that. If I were you, if the lights were off before, it's very likely that you disturbed something in the process of installing your gauges. Go back and check nearby wiring connections even though they may look fine. Unplug them and plug them back in nice and snug. Also, first thing to do is disconnect your batteries and leave them disconnected for 10 mins. Also push the brake pedal while it's disconnected to eat up any remaining energy in the system. That should reset the computer.

infidel

I think the wire you removed was the ground for the ABS unit. In disconnecting the ground you in effect turned the ABS off, computer recognized it as a failure..
Brake problems set a hard code which is one that doesn't go away even after the problem is corrected. Sometimes you can get the lights to go off by disconnecting the batteries. Some hard codes require a scanner or to wait for the truck to go though 50 run/stop cycles before they are canceled.

In the future never do electrical work while the engine is running especially involving a ground. Modern computerized systems don't like it at all.

TIMMY22

Usually, the only way this works is to disconnect both batteries (in a 2 battery system) completely and hold the POS and NEG together on each while you depress the brake pedal. This discharges the capacitors.

CC149

Well I did the battery unhook thing and the lights went out, and so far have stayed out. Unhooking that black wire must have been what caused the lights to come on. Thanks all.

Jim