Very weird electrical fault

Last night at the track, I noticed the car doing weird electrical things. Knowing something was amiss, I bugged out of what turned out to be the last two runs.

It was after dark, and I slammed the hood to get ready to run, got in and turned the key on when the lights 'sort of' came on(lightswitch off), the speedo was jumping around and the left turn signal indicator was on(solid - no blink). Turning the light switch on caused the PS HID to come on, the DS HID to make a rapid blinking. By this time the speedo was back to normal but I know the engine was warmer than that indicated - the temperature gauge was all the way down. The turn signals do not work.

I got out of line, went to the pits, changed tires, let the car cool and tried to troubleshoot. I could find no 'smoking gun'. Sure seemed like a short in something. The best lighting was with the headlamps on high beam. The HIDs were out and only the PS high beam was lit. On low-beam, the DS HID kept flickering and the PS HID was on - and the DS HIGH beam was half lit???

Then all of the sudden it reverted back to normal. Lights on and off with no issue. Turnsignals work. Everything's fine. Time to head home. Shut the hood and 'here we go again'! Same symptoms. More troubleshooting... nothing... and I think the cooling fan is only partly running. Anyways, eventually I take it on the road headed home with one high beam(thank goodness for HIRs!). On the way back, passed through a toll booth and once out of the overhead lights, I noticed the lights were back to normal! Both HIDs were on, the high beams were on, turn signal indicator was off and the turn signals worked!!

Arghhhh... hit a bump a few miles down the road and I'm back to one high beam and weird stuff again. Stop at McD's and park and eat. Get back in the car to leave and... you guessed it... back to normal. Drove the rest of the way home no problems - avoiding 'bumps'.

Anyone with any ideas?

BTW voltage check was 13+ running.

I had a ground issue on the ancient 95 with exactly the same symptoms.

Check the litte tiny grounds on both sides of the front header panel, they tie into that entire front headlight wiring harness. Maybe something there?

One more vote for grounds. The EX's 97 T bird was going nuts and the turn signal was exibiting similar problems. It also caused the HVAC to go haywire, the lights to dim etc etc.

I checked a HUGE ground junction under the steering wheel and one of them had a positive voltage (not cool) so I ran an additional ground from the grounds. lol and Voila problem fixed, for the past year.

I concur. Visible checks on the ground points under the hood showed nothing out of the ordinary. In my experience, bad grounds exhibit very bizzare symptoms.

I guess it's time to get out the EVTM. Max, exactly where "under the steering wheel" is this major ground splice? Strange that ground would be suspect since slamming the hood appeared to be the trigger.

I had to remove some interior pieces to get to it... it may be different different location in the mark.

I had to get on my back, rest my head on the brake pedal and look straight up. For lack of a better description. Boy was it fun.

Here is my post from TCCOA. "I located right behind the steering column. You don't have to take off any panels but you do have to crawl up to the brake pedal. Then look straight up and you're going to see a black plastic panel about 12 inches above your face... there are 25 black ground wires going into C 2014 you really can't miss it. Hope it helps. Thanks."

http://forums.tccoa.com/showthread.php?t=82510

Also.....before you get side tracked on the grounds, a shorted wire TO ground would also give you crazy symptoms. Just double check the entire harness at the front and in the area of the hood being slammed....I bet there is something pinched or some insulation is rubbed off somewheres.

J said:

Also.....before you get side tracked on the grounds, a shorted wire TO ground would also give you crazy symptoms. Just double check the entire harness at the front and in the area of the hood being slammed....I bet there is something pinched or some insulation is rubbed off somewheres.

Click to expand...

That was exactly my first thought and I initially looked for such but found no suspect areas. I'll hopefully have time this weekend to dig deeper.

Good luck dude....I simpithize you GREATLY! I absolutely HATE electric problems because I don't know crap about using my Volt meter except when checking for power/ground.

I checked all the grounds today and cleaned them. I looked high and low for any shorts to ground and found none.

The one anomaly I found was the digital fan controller was not working. Coincidence? I think not. I was measuring voltage on the ground switch output that completes the ground path for the over-ride fan relay. That relay system is grounded at the header panel - same as the lights. I removed the controller for now and rewired the over-ride to a manual control.

Everything tests fine, even after slamming the hood several times. I'll keep my fingers crossed. The road trip to WFC @ Indianpolis is coming up this week. Gotta get the car cleaned up, change the oil and figure out how to pack everything.

electrcal

electrcal

If you find an answer, let me know. I'm having similar problems.

jp
thought from the far side...

Check connections around your HID ballasts, since they are located in the bumper cover area, you might have something jostled around when you slammed the hood.
*grabs at a straw*

Apparently it was the digital controller. After it was pulled from service and the cooling fan over-ride rewired around it, all has been well.

I'll eventually get around to ordering a new one. I want to rewire the whole setup anyways and move the electric pump wiring as well while I'm at it.