Both rear turn signals erratic
 

No rear turn signals, hazzard or side brake lights. Yes to center brake light.
Seems like we are again the first with a new issue! Lucky us haha. A least this time not major like the shredded engine block, and hopefully not as bad as the whole (hole) radiator issue! (Which they still seem to refuse to own up to the defective design of!)
Anyway . . . . !
Since last September the passenger rear turn signal on our '07 H3 burned out, then again in January. Maybe just a fluke. Then last week this began . . when turning right, signal will blink normal then maybe fast, then it would or would not go back to normal. No rhythm or reason. Then yesterday . . . Same thing is now happening with the driver side. Checked both bulbs appear ok, but while in fast blink we know - NO rear turn signal and No rear brake lights. (except upper center bar light thankfully!). When goes back to normal works fine! In the morning, IF the rain has stopped, we're going to swap out both bulbs just in case. So hate random part swapping if can be avoided (who doesn't yes I know!) Wondering best place to start. The actual signal switch on column? This is our best guess. And if so, any leads on best place for a part? Also looks as of it does make a difference that we have a manual transmission. Looks like pricing between $160 and $220 for an OE? Also if anyone has changed this part, any tricks? hoping is as easy as our ignition switch replacement was. Then I suppose it still could be an issue with a signal relay, or if the BCM that controls both, could that be going bad and it needs replaced? Love help suggestions from anyone had this issue,
This is daytime driving with headlights auto on. In motion or stopped.
Any help as always, appreciated.

Otherwise our H3 been a pretty good utility vehicle, we’re up to 110K miles on the unit and about 40K on the new engine. Husband modified radiator bracket slightly and watches for new cracking. Still getting a rather standard 20mpg plus or minus 1mpg whether on highway or in town. No worse than our Dodge diesel and doesn’t matter if we have a heavy load or not.

Have you checked the harness that is under the back side of the rear frame. There is a harness back there that rubs and shorts out.

On your back, head facing the front, look around the frame cross brace closest to the rear bumper, center to driver side. There will be a harness there.

I have seen a few rub throught the insulation and cause some "strange issues".

Thanks Tainter,
Worth taking a look.

the fix for that harness is to push up and forward till it clicks loose where it connects to the frame.
if its worn thru,you need to tape insulation on it.
the way its mounted,they all are at risk.

X2 on the trailer lights wiring harness. If you open up the tailgate, look between the bumper and the body. It may have rubbed through the insulation.

Rear harness looked good, no wear spots or scrapes. (But worth checking regularly anyway now.) We have found while signal is on and blinking fast . . .turn the steering wheel ever so slightly . . . signal returns to normal . .Thinking a break in that column harness. Or issue in the rotor (?) of the signal contact . . . Back to thinking is associated with this switch area component.
Thanks for any input.

if its a snug fit /tight now you can avoid the future problem by popping it loose now,,jfwiw

Still chasing gremlins!
 

We're back to rechecking and double recheck the wiring harness :-(
Yes we have tail running lights
No we do not have rear turn signals or hazard or rear side brake lights
Yes we have the rear center brake light.
We have changed the darn turn signal switch / multi switch assembly in steering column
We know that the rear sides are also controlled by the left brake pedal switch which when wires pulled and jumpered - still nothing to rear. (right brake pedal switch is for center brake light and does work)
Replaced the fuse for the: Rear Turn hazard. No help
Have been doing inch by inch visual check on harness from back to front . . . just not finding anything that has shows pinched or rubbed, or wear issues. No damage to out plastic conduit.
So hate having to drive big diesel daily but sure as heck do not rear ended by any of the crazy tail gating speed demons we have out here!
So any more hints out there would be so appreciated!

Throwing in the towel
 

OK thinking we're at the end of our ability to solve this issue.
Thinking on progression of issue.
First was only right rear signal issue,
Then after nearly a week it progressed to left rear signal issue
Then realizing included brake light issues!
As we understand it. You actuate signal on column, this then goes to BCM then distributed to where needed. As we can find no fuse or wiring issues we hate to say it but thinking could be a BCM issue?
Is this too far out? Do these fail more than shown here?
And IF a BCM issue this looks like a Dealer fix only option as has to be programmed to match all our computer system, correct? We have no electrical add ons, nothing to mess with the system. But think this requires the shops special electronics to handle?
Besides the fact that we're just out of ideas, and want our H back.
Dreading the wild wide range of estimates we've seen here on shop replacement of this component!

Had the same issue with my 06. I went and bought high priced sylvanias and it seem to work. I went thru 3 sets of the OEM ones before buying the high price ones. Haven't had a problem in 2 years. Just a thought. hope you get it sorted out. I hated changing those bulbs every other month!!