How on earth do you fix electrical issues?

"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
10/20/2014 at 09:49 • Filed to: None

Right now electrical gremlins have caused my rear wheel speed sensors to report inaccurate readings and disable my ABS, which my dad is screaming at me to fix, as well as spastically disabling my security system and causing a Service Vehicle Soon light to come on for brief moments in time without throwing any codes that my reader (which can read GM specific codes) can find. Also the ABS light flashes a couple times when I start the car and I can't remember if it has always don't that or not.

As for the ABS, I replaced both hubs assuming the speed sensors were bad, and that didn't fix the issue.

DISCUSSION (19)

Nibby > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 09:50

THIS COULD BE YOU. Be careful.

Kinja'd!!!

RamblinRover Luxury-Yacht > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 09:55

I'm guessing when you replaced the hubs, the encoding surfaces got replaced. ABS flash on start once would likely be normal, but multiple may be a fault status. The other two - no idea.

Strong argument for a car with a paleolithic electrical system, IMHO.

ttyymmnn > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 09:56

Have you googled it? There's every reason to suspect that you are not the only person who has had this or similar problems.

Jake - Has Bad Luck So You Don't Have To > RamblinRover Luxury-Yacht
10/20/2014 at 09:58

Yep, and my dad is insisting on fixing it on a car barely worth scrap value and with 229,000 miles because "WE KNOW ITS SERVICE HISTORY!!!111".

Jake - Has Bad Luck So You Don't Have To > ttyymmnn
10/20/2014 at 09:59

Been googling. Only explanations are: light bulb out (not the case), fuse blown (not the case), PCM is dead (no clue), wiring harness has a short somewhere; replace harness (probably the case).

EL_ULY > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 10:00

Voltage drop tests.

ttyymmnn > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 10:01

Good luck. I have no idea.

Jake - Has Bad Luck So You Don't Have To > EL_ULY
10/20/2014 at 10:01

As in, look for voltage drops across the whole system? It's at a steady 14 volts.

RamblinRover Luxury-Yacht > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 10:03

Security system - maybe bad door sensors or something? I'd assume it to be a wear item, basically, so it might be either bad door-close sensors or lock position sensors.

It could just be that you have a bad connection somewhere in the wiring going back to the wheel, if the sensors and encoders are all fresh.

As to the *check engine*, there are things that are not ECU controlled that trip that sometimes on GMs. Could even be something like a bad connection on the low-coolant sensor. We have an 80s 'Burb that has a gas EFI body on slightly older diesel mechanicals (rewired) - and the check engine light came on briefly the other day. "wat". Turned out it was a coolant warning.

EL_ULY > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 10:14

Is there a code for a specific side?Can you swap sensors from one side to the other see if it changes?

Jake - Has Bad Luck So You Don't Have To > RamblinRover Luxury-Yacht
10/20/2014 at 10:15

Door-ajar system works flawlessly. I don't believe lock position is a thing; its logic is "I just got a lock signal from the fob. *locks doors* If they get unlocked from the inside something's fucky" and this logic is correct... most of the times. If I lock it with the fob then reach in and unlock the door from the inside it will set off the alarm when I open the door (but not from the act of unlocking it). If I wait a day or two and do the exact same procedure when the security system is acting up, it wont do that.

That wiring is so buried under layers and layers of heat shields, rubber coating, and wiring loom... ugh.

But how could I tell? It's throwing no codes that any equipment I have access to can read.

Jake - Has Bad Luck So You Don't Have To > EL_ULY
10/20/2014 at 10:17

I got brand new sensors (in the hubs) and nothing changed, so it's gotta be wiring or the ABS controller itself.

It was an individual code for the left rear side, and a different code for the right rear side.

RamblinRover Luxury-Yacht > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 10:21

My Benz has lost two of the disabling switches for the security system that are supposed to operate when you open the passenger or driver's door with the key. So, if I lock the car, the alarm goes off unless I unlock it from the trunk. HURR. If yours has anything remotely similar to that, that may be the something fucky you're looking for, failed in the other direction.

EL_ULY > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 10:36

First though, remove both hubs and see if it changes to eliminate a bad part. If the code changes, bad part just to be sure. Bad new parts do exist and they will eat your lunch. If the code doesn't change, i'd try to find out which is the signal, power, and ground wires. Do voltage drops tests up to the ABS module. There is a possibility it might be linked with Cruise Control and SRS. Have some one activate the hall sensor with key on while checking.

A GM scan tool will be able give you specific error codes from different ECU's not just the basic engine ECU. But... that would be impossible to have right now :(

Key is to do the proper diag BEFORE replacing parts. Even if the parts are inexpensive.

Jake - Has Bad Luck So You Don't Have To > EL_ULY
10/20/2014 at 10:58

By "remove both hubs" do you mean to unplug them from the system or replace them with the old hubs?

EL_ULY > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 11:06

not sure if they can be swapped from side to side to test. Just to eliminate the potential of a bad part. If the code changes, then bingo. If it stay the same, the parts (new and possibly old) are good and it is something else

davedave1111 > Jake - Has Bad Luck So You Don't Have To
10/20/2014 at 15:12

How to fix electrical issues:

1) Work out what's wrong.

2) Repair or replace whatever's broken.

But seriously, trouble-shooting electronics is just like any other trouble-shooting. You need to exclude as much as possible from the equation so that you can test things one by one.

With the ABS, have you checked the rings as well as the sensors? And that you have the right spacing? It's quite important to fix before you drive the car, particularly in the wet, because cars set up for ABS can be a real handful without it because the rear wheels can lock before the front.

For any other odd electrical problems, first check your earths, then if they seem fine, recheck them, test them, and check again.

gmporschenut also a fan of hondas > Jake - Has Bad Luck So You Don't Have To
10/21/2014 at 00:52

Sounds dumb, is everything fully connected? Did you try contact cleaner on all the connections?

Jake - Has Bad Luck So You Don't Have To > gmporschenut also a fan of hondas
10/21/2014 at 08:34

No corrosion on anything, though I didn't use any cleaner.