[Jason B]

I'm starting a new post on this here. I was having this weird shifting all of a sudden and couldn't figure out how it was happening. I just realized what was making it happen! If I put my left turn signal on or right turn signal on, that's what causes it to upshift and get confused with the gears! but only when I put the turn signals on... I have a '97 limited. I just pulled out my gauge cluster and will attach pics. Never a check engine light either.

BUt how do I know if it's that board that's bad? Another thing, if I drive without the gauge cluster OUT for a short drive and put my signal on and it doesn't do the crazy shifting, then we know it's that board 100%? The signal makes it do it every time normally.

Originally Posted by phattyduck

Wow, what a crazy one!

Based on your tests, it is definitely something with the gauge cluster. Check all those traces really carefully...

Especially the wires from the section of the cluster with the gear indicators and the turn signal bulbs (anywhere those traces get close to each other).

Good luck!

You probably can get a replacement cluster and just swap in your speedo/odometer...

-Charlie

Thanks to @phattyduck and also @thegipper for telling me to look at the board, just not sure where to look

[AntleredRuin]

I had some issues with cruise control kicking off and on when I used my turn signals.
I'm not sure of the all electrical details, but basically, the issue was the LED bulbs I used. I put back in standard bulbs and the issue was fixed.
Maybe related?

[Jason B]

Interesting. I've had that same bulbs in for years, and it just started not long ago.

Video of issue:

http://www.youtube.com/watch?v=40fAGOfDr38

[AntleredRuin]

I had mine in for a few months before it started happening.
I just got the cheapest Sylvania LEDs that would fit that Walmart sold. I got a warning from a cop earlier that a light was out and I was heading by Walmart anyways. They were out of the standard at the time and the LEDs were only a couple bucks more.
Fit and worked fine, but fast-forward a few months and my cruise control started acting up. On closer inspection, a bunch of the SMDs on the bulb were actually flickering a lot. I wonder if it was a bad batch of bulbs?

[thegipper]

Hmmm...

It looks like the OD is kicking in and out when you use your turn signals. It may not be that circuit board but something else. Perhaps a short in the wiring or something. What does your OD button do if you try using it? Does it still work?

[phattyduck]

Originally Posted by thegipper

Hmmm...

It looks like the OD is kicking in and out when you use your turn signals. It may not be that circuit board but something else. Perhaps a short in the wiring or something. What does your OD button do if you try using it? Does it still work?

That's not downshifting, that's just the torque converter unlocking. Even more weird!

-Charlie

[JayRolla]

Ive heard of this a few times and everytime someone mentions this issue they tend to have LED headlights, signals, ect.. Kind of strange.

Researched a bit and people have fixed it finding bad grounds at turn signal bulbs, ect... LED bulbs at the signals causes it on some fords and dodges.

[DK327]

Do all your lights work? Brake lights, turn signals, etc... Asking because:

"it turns out that one night my dad was behind me and said my L/H brake light was out. By now I was living with the torque converter unlocking with the R/H turn signal. And low and behold after I changed the L/H brake/turn signal bulb the torque converter stopped unlocking with the R/H turn signal. Don't ask me but it did fix it."

That post was for a Ford Bronco, but might be a clue, as well as this one:

"Your turn signal is back feeding your stop lamps. Check your trailer wiring harness at te back and tail/ turn bulbs. What happens is when you step on the brakes the stop switch on the pedal tells the transmission to come out of lockup for decel."

the OP's resolution to the above post:

"Got both taillight harnesses fixed and the problem went away. I guess this is fords way of telling you that you have a taillight burnt out."

Good Luck!

[Jason B]

Ok, well I went for a drive with no speedo cluster in the vehicle at all (it's sitting on my desk) and same thing happens. Does this automatically eliminate the cluster as the problem?

Originally Posted by thegipper

Hmmm...

It looks like the OD is kicking in and out when you use your turn signals. It may not be that circuit board but something else. Perhaps a short in the wiring or something. What does your OD button do if you try using it? Does it still work?

OD still work, and the problem will still happen with overdrive on or off. It will still jump around when signal is put on.

Originally Posted by DK327

Do all your lights work? Brake lights, turn signals, etc...

Yes...

And I found out a little more WHEN it will happen. After the truck auto shifts in to 5th gear, that's the only time the signals will make it jump around, all other gears it doesn't do it. So, starting out from a stop in 1, 2,3,4, and only happens when it's in 5th, after the last shift.....

[AntleredRuin]

If you have an auto, you only have 4 gears.
Do you have any LEDs in the back? There's 3 different bulbs. If so, trade them for stock. That's a simple enough test there

Sent from my SM-G900V using Tapatalk

[phattyduck]

Originally Posted by Jason B

And I found out a little more WHEN it will happen. After the truck auto shifts in to 5th gear, that's the only time the signals will make it jump around, all other gears it doesn't do it. So, starting out from a stop in 1, 2,3,4, and only happens when it's in 5th, after the last shift.....

Ain't no 5th gear on the auto. That's torque converter lockup. Still 4th gear, but without any slip in the torque converter, so RPMs go down. Same thing happens in 3rd if you have O/D turned off.

You can probably get it to do the same thing by lightly stepping on the brakes when at cruising speed.

So, now to figure out if it is damaged wiring or those aftermarket LEDs in various places...

-Charlie

[Nate_GB]

Originally Posted by Jason B

Ok, well I went for a drive with no speedo cluster in the vehicle at all (it's sitting on my desk) and same thing happens. Does this automatically eliminate the cluster as the problem?



OD still work, and the problem will still happen with overdrive on or off. It will still jump around when signal is put on.



Yes...

And I found out a little more WHEN it will happen. After the truck auto shifts in to 5th gear, that's the only time the signals will make it jump around, all other gears it doesn't do it. So, starting out from a stop in 1, 2,3,4, and only happens when it's in 5th, after the last shift.....

Personally, I don't think it has anything to do with the cluster. I would check the harness for the right and left brake and tail lights. I think the other suggestions in this thread are on track. If the turn signal wiring is shorting on the brake light wire, it could cause the truck to think you're slowing down and cause the truck to think it needs to unlock the torque converter. Also, your truck has 4 gears. 3 under drive and 1 overdrive. It can sometimes feel like a "5th" gear shift when the torque converter locks up.

[Jason B]

Thanks everyone... I do have led tails, but, have had them for years, and also have a led hitch brake light. That's it. Also had for years....

IF I UNPLUG both tails, and it goes away, that's my issue?

Also, it doesn't matter of the headlights are on or off when this happens. And the turn signal bulbs are just filament bulbs.

[octanejunkie]

Originally Posted by Jason B

Thanks everyone... I do have led tails, but, have had them for years, and also have a led hitch brake light. That's it. Also had for years....

IF I UNPLUG both tails, and it goes away, that's my issue?

Also, it doesn't matter of the headlights are on or off when this happens. And the turn signal bulbs are just filament bulbs.

LEDs don't draw as much voltage, or create the same resistance as incandescent bulbs; they are diodes. The vehicle is anticipating a certain amount of voltage drop in the circuit when lights are used. Bad wiring usually increases resistance. Wiring shorts cause voltage drops. Any of these "issues" may be contributing to your problem.

I doubt it's one problem, it's probably two issues; one exacerbating the other. Go get a cheap set of regular tail bulbs and see if your issue goes away for the time being.

[Jason B]

The only LEDs I have are the led tails, which the only part that is led is the bottom half. The turn signals and reverse bulbs are all regular plain bulbs.



But these were not the issue. I disconnected both rear tail harnesses and same issue.

The ISSUE IS FIXED AND WAS A BURNT OUT 3RD BRAKE LIGHT BULB! I can't believe this and how i missed it. I just had the truck inspected like 2 months ago and all lights were working and this whole thing started about a month ago. I put a gallon jug of windex on the brake pedal to test, and sure enough, 3rd brake not lighting up! Same bulb in there since 1997! 20 yr old bulb (Koito 18 watt), and it was charred and bulb glass a little warped. Pulled the bulb out and went for a test drive. Same issue, until I put in a NEW bulb, and then it fixed the issue!

A few questions.

1) Why does a new bulb have to be installed to fix this? Seems odd, but maybe just this specific location, 3rd brake light causes this?

2) Now I can make the issue happen by hitting the brakes with the gas on, like someone else mentioned (which is normal, torque converter, and that's what was happening when I signaled with the burnt out 3rd brake bulb.

Also funny how you must remove the spoiler to install a new 3rd brake bulb.