RPM SPIKE WHEN LEFT TURN SIGNAL IS USED

[Coltonreece]

Okay so I have a 7.3 idi na f250, I made a post a few weeks ago saying that on my highway, when accelerating in higher gears, my rpm’s would spike, and then jump right back down, ( talking probably 100rpms give or take) someone pointed towards the torque converter. Well just within the last few days I’ve noticed that it only happens when I turn my left turn signal on ?? What could cause this ? I thought it was due to highway acceleration because when I merged onto the highway I’d always use my left signal. Any ideas at all ?

 

[Rocknit4x4]

Does the engine actually speed up or is it possibly just the tach jumps?

 

[IDIBOBS]

The torque converter is unlocking because it thinks you pushed the brakes. You need to replace the multi function switch in the column .

 

[Jesus Freak]

Lol, E4ODs sure are weird......

 

[IDIBOBS]

Lol, E4ODs sure are weird......

It’s not really a symptom of the E4od. Any transmission is going to unlock the TC if you press the brakes. And the brake circuit goes through the turn signal switch. Pretty common. The turn system in the pre 94.5 trucks hasn’t changed since the 60s.

 

[YachtTech82]

Can't LED bulbs cause some weird TC stuff too?

 

[IDIBOBS]

Can't LED bulbs cause some weird TC stuff too?

Yes for sure. But they cause issues even with no lights on. The computer for the E4od looks for ohms to ground of the bulb when the bulb is off. LEDs don’t have any resistance so the computers gets upset. Same happens if a bulb is out. You can buy ressistors to solder in to fix this and f you really want to run leds.

 

[Greenie]

I never could understand how power applied to a turn signal (same filament as brake light) didn't back feed. That magic must happen in the turn signal switch.

 

[IDIBOBS]

I never could understand how power applied to a turn signal (same filament as brake light) didn't back feed. That magic must happen in the turn signal switch.

Yes it does it’s some kind of magic.

 

[Jesus Freak]

It’s not really a symptom of the E4od. Any transmission is going to unlock the TC if you press the brakes. And the brake circuit goes through the turn signal switch. Pretty common. The turn system in the pre 94.5 trucks hasn’t changed since the 60s.

I've never had my ZF-5 act up when Ive turned my turn signal on.

 

[Jesus Freak]

I never could understand how power applied to a turn signal (same filament as brake light) didn't back feed. That magic must happen in the turn signal switch.

....tis voodoo, senor....evil voodoo....

 

[KansasIDI]

Some newer vehicles have a separate brake switch for the transmission. Some controllers, like the Baumann, have a finer range that the torque converter is supposed to be locked, or unlocked. It’s also supposed to be adjustable with a Baumann.

After reading about the factory system and its idiosyncrasies, I bought a Baumann for my 94.

At any rate, with an old electronic transmission, this is how it is.

 

[Brian Wagner]

Does the engine actually speed up or is it possibly just the tach jumps?

Hey Colton, I don't see where you answered this question, and I'm curious as to the answer.

 

[Jesus Freak]

Hey Colton, I don't see where you answered this question, and I'm curious as to the answer.

These are the unanswered questions we live with on the forum.......try not to loose sleep over it, though it is hard sometimes..... especially when the OP title is in all caps....