I have a 96 f250 that the cruise was working on until I put on the new flat bed with LED tail lights. I am leaning towards there is not enough resistance in the circuit with out the old style lamps.

I wired the black <ground> to the white on the new lights. The brown goes to the <TAIL light> wire on the LED light and the green striped goes to the red <stop/blinker> Right?

Has any one ran into this?

 

Yep, the old school cruise module needs the resistance of old school bulbs. You can get a resistor (sold as a "load resistor") that wires in parallel with the LED's, but these tend to get hot since the power has to go somewhere (resistors dissipates it as heat) and can melt things. I'm sure with some creative rewiring it's possible to leave the LED's alone and get the cruise working as well, but without schematics I can't help with that.

 

If you have an electronic auto trans, those LEDs will make it do some weird things, too! Like shift up and down to the rhythm of the turn signal. Even the smallest "regular" bulb wired into the circuit containing the LED will make it go back to normal.

 

Dixie460 did you mean wire the resistor in series (not parallel) with the LED lights?

I've heard of this issue before. Interested as I'm soon going to be flat bedding my rig too, and like the idea of LED's but also want to get it right the first time.

 

Nope, I meant parallel. One lead to + and the other to - so that the resistor can draw as much current as it's internal resistance allows. Just like the filament in a plain bulb would.

Someday here in a bit, I'm gonna sit down with the schematics and figure out how to keep the speed control AND transmission happy while also being able to run full LED's without resistors. Already got the turn signal situation figured out... all I did was get a non-load-sensing flasher relay.

I want to run LED's but ain't even looked into this yet since my speed control servo is dead (so I wouldn't be able to test it) and also I don't have the schematics right now anyway so I couldn't track down the transmission issue either.

 

Okay, I wired in my load resistors on the brake light circuit and still no cruise. I also have no reverse lights but do not no if this is related. Any one have an EVTM of the cruise circuit and reverse lights? It hit me to test my cruise cancel switch on the master cylinder and It stays closed all the time. Is it N/C or N/O. I would think it would be normally closed and go open when the brake is applied. Thanks

 

Yes, that switch should be N/C at rest and go open when you hit the brakes.

Sorry I can't help with the EVTM...