Another E4OD Question ??

Reply Subscribe

Thread Tools

Search this Thread

Jun 25, 2024 | 10:26 AM

milmat1

Thread Starter

4wd Low

Joined: Apr 2024

Posts: 13

Likes: 2

Another E4OD Question ??

1992 F150, 2WD, 4.9L / E4OD.

I seen a reply that mentioned LED tail lights causing issues with the E4OD transmission.

Can someone explain this to me.

I know my E4OD pretty well and I understand the tranny control from the PSOM/ECU to the solenoid bank.

But I fail to see the connection to the LED tail lights ???

ANYONE ??

Jun 25, 2024 | 12:16 PM

Junktownbill99

Fleet Mechanic

Joined: Nov 2022

Posts: 1,695

Likes: 415

I can't imagine any connection between LED tail lights and the transmission, however I've heard they could cause issues with turn signals.

Jun 25, 2024 | 12:33 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,695

Likes: 2,616

From: SE Florida

The PCM looks at the brake light circuit and uses that input as one part of the decision to lock or unlock the torque converter. Installing LEDs changes what the PCM sees and it thinks the brake lights are always on. This can delay or even prevent the torque converter from locking.

Jun 25, 2024 | 01:31 PM

milmat1

Thread Starter

4wd Low

Joined: Apr 2024

Posts: 13

Likes: 2

Quote:

Originally Posted by Mark Kovalsky

THANK YOU !!

I may be onto something here then. Because the PO has installed LED tail lights in this truck. That may very well be my issue with the erratic acting tranny..

Thank You !

Jun 25, 2024 | 02:35 PM

Duke5A

Tuned

Joined: May 2024

Posts: 298

Likes: 147

You're going to need load resistors then if you want to keep the LED taillights.

Coming across this probably saved me a future headache. The bed is off of my truck while I rebuild the back half of the truck. Was going to swap in LED taillights during reassembly.