No downshift and turn signal unlocks TC

[Martinique78]

So this is my first PSD truck and i'm finding the way it drives a little annoying. First of all there doesn't seem to be a passing mode. While cruising around at 30-40mph and mashing the throttle it never kicks down a gear and accelerates. It just slowly climbs up in speed and sometimes it almost feels like it upshifts. Is this just a nature of the beast or do I need to be looking for something?

Another problem I have it that using the turn signal unlocks the TC at freeway speeds and will shut off the cruise control too if it's engaged.

[Patrick Feeley]

Look for a burned out bulb for the turn signal issue (its a Ford thing). Cheers!

[madpogue]

Specifically, check the center stop light in the cab roof.

[Martinique78]

Checked all my bulbs and they are good. Plus my truck is a 92 so no high mount stop light. I did have to do some wiring modifications to the harness when I installed the 96 PSD setup. I should probably check those areas first.

[madpogue]

Originally Posted by Martinique78

Plus my truck is a 92 so no high mount stop light.

There's your trouble. That's the same as the bulb being burned out. You need to put a dummy resistor in the brake light circuit where that center stop light would go.

[Martinique78]

Really? that would cause that much of a problem? What size resistor would I need to put in? do I just connect the other end to ground?

[madpogue]

Yup, when that light is burned out (or in your case, just not there), and then you hit the turn signal, since the turn signal bulbs on the bed are the same filament as the brake lights, that causes some kind of sneak circuit back to the brake light wiring, making it look like you've hit the brake pedal; the PCM picks that up and unlocks the TC and interrupts the cruise. This is why I love that my wife has both ZF5s (she won't drive an auto); yeah, you lose the cruise, but then you just hit Resume.

Not sure what rating of resistor. Probably something similar to what some guys use in conjunction with LED bulbs, for similar issues. Should work to just ground the other end. This _has_ to go in the brake light wire that comes right from the pedal switch, _not_ one of the wires going back to the bulbs in the bed (since they go through the turn signal switch).

[Martinique78]

Originally Posted by madpogue

Yup, when that light is burned out (or in your case, just not there), and then you hit the turn signal, since the turn signal bulbs on the bed are the same filament as the brake lights, that causes some kind of sneak circuit back to the brake light wiring, making it look like you've hit the brake pedal; the PCM picks that up and unlocks the TC and interrupts the cruise. This is why I love that my wife has both ZF5s (she won't drive an auto); yeah, you lose the cruise, but then you just hit Resume.

Not sure what rating of resistor. Probably something similar to what some guys use in conjunction with LED bulbs, for similar issues. Should work to just ground the other end. This _has_ to go in the brake light wire that comes right from the pedal switch, _not_ one of the wires going back to the bulbs in the bed (since they go through the turn signal switch).

Thats f-ed up. I just have the pigtail that would have gone to the third brake light taped up under the dash where it would have gone into the connector going to the back of the truck. Could I just tie it in there? Should I just measure the resistance of a bulb and put the same resistance size in there? I'm guessing it's going to have to be a high wattage resistor.

[BigFuel]

50W resistor. These get hot so get one with cooling fins or it may melt anything else touching it.

[madpogue]

Originally Posted by Martinique78

Thats f-ed up. I just have the pigtail that would have gone to the third brake light taped up under the dash where it would have gone into the connector going to the back of the truck. Could I just tie it in there? Should I just measure the resistance of a bulb and put the same resistance size in there? I'm guessing it's going to have to be a high wattage resistor.

Yeah, should work to plug the resistor into that pigtail. Resistors are measured in ohms, so yeah, measure the resistance of a 912 (is that it?) bulb and match.