2000 C5 directional issue
 

directional's have been intermittent with hyper-flashing, left inop, right inop etc,
assumed 4 way flasher.... bought new flasher and just got done replacing it. miserable job and it didnt work.
Both directionals are hyper-flasing the rear bulbs.... new bulbs in front, same result.
cleaned left and rt grounds at chassis behing headlights no luck....
assuming a bad grouns somewhate any thoughts

Check the multi pin connector just behind the passenger rear wheel. This is the harness for the rear taillights. A friends car had the ground wire fail on the car side of the harness causing a multitude of lighting issues, no taillights, hyper flashing, no brake lights.

We had started with the usual suspect the multi-function switch but found quickly that was not the problem. Ended up moving the ground wire out of the connector on the taillight harness side and attaching it to the ground post that is right there. Due to other issues, I ended up doing a complete rebuild on the harness.

Gary

It's actually the fronts that don't work intermittently, the rears always work, except they fast flash or as i call it hyper-flash when the problem occurs....
It started a year ago with the left front only, then moved to the right front, then it would be both left and right front.
I put in new bulbs 2x, cleaned the connections checked best possible all grounds? seemed related to heat so i was positive it was the flasher, no luck here, put in the flasher yesterday and nearly shot the dash when the problem repeated....(whoever designed this flasher mount should be shot):smash:

When it hyper flashes the bulb in front wont blink, nothing..... but if i pull the bulb put a test-light to the positive, the test light will blink in hyper mode.... this lead me to suspect the ground but even supplying an auxiliary ground to the socket with the bulb plugged in doesn't to it.
then it suddenly stops and its fine for a week, then it repeats.

I'm thinking of trying the multi function but at $200 id like to see if there are any other thoughts or opinions on this switch thought or if someone has other connectors to try...... I hate like hell to turn a tech at the dealer loose with an electrical gremlin...:rofl:

I had the exact same problem with my '97, where the fronts didn't work intermittently, but the rears always worked.

When I went to replace the turn signals, I found the contacts all corroded, burned, and even seemed to be a little loose. I ended up buying new Turn Signal Lamp Sockets for the front left and right turn signals, cutting the old sockets off, and then soldering the new sockets to the existing wiring harness, which solved my problem. I finally have working turn signals!

Rock Auto has after market Turn Signal Lamp Sockets for about $6 each, or the factory AC Delco ones for about $32 each. Might be something to try?

thanks, the front sockets are clean as can be ...... appreciate the advice

Check the hazard flasher. The turn signal circuit goes through it. Try pushing it the hazard light switch on and off a bunch of times to clean the internal contacts. If the turn signals starting behaving, you may need to replace the hazard switch. It's a pain to replace.....

Check/Clean SP102, SP100, and G102 and see if that fixes it. Those are the splice packs and ground for the front turn signal lamps and other things.

Reread your post and I guess you've already done that. Check the ground wires from the bulb sockets to ground with a meter.

I'd cleaned SP 100 and SP102 when it initially did this funky fast blink act....
Sometimes its the left side, sometimes its the right, sometimes both. When this happens, the rears always fast flash with the front bulb inop.
Since the new 4 way didn't fix it, I've ordered a multi-function switch ??
In testing everything, if i ever so gently / slowly put either the left or right directional on, the directional on either side will first start to fast flash before you get to the full on position so I'm hoping its multi function.:smash:

Just in case anyone followed this....... it turned out to be TWO defective turn signal relays.

That's great, glad you finally got it fixed, even if it did take a year and 9 months, Good find, and persistence pays off.