The ONLY reason I suspect it's supposed to be energized is that it throws a code when I unplug the things. It would need to power them to be able to detect them at all, right? So maybe "power up both solenoids" is part of the start sequence, and it powers them until it gets a reading, or something? Does that sound logical? I should try unplugging it AFTER the key has been on for a minute next, last time was unplug, then turn on.

 

Same result if I turn it on and leave it for a minute. Unplugging it throws those two codes, and it still has 12 volts to both sides. If both solenoids are stuck on, it seems like I would have noticed that by now, right?

 

One would think so.

According to theory, trans receives power from the ASD relay. So, you should only see power down there for a few seconds at key on..... Though, that is how the 2nds gens work..... 1st gens are apparently different. So, it wouldn't much of a stretch to figger the whole system ain't quite the same. I would need to have a service manual to look at to say for sure. But, if it sets the codes with just key on, and the truck never moving...... That is passing strange.....

 

Well there's a fun one. This thing doesn't have an ASD relay, that I know of. The spot where it goes is an empty socket.

 

LOLOL. Yeah, so, my knowledge is pretty much useless then. I wouldn't think that the pcm would BREAK the circuit to apply those solenoids, but, that is entirely possible....

Ok, found a diagram online. They are called "lockout solenoids", so, apparently, breaking the circuit does indeed apply them. If I am reading the diagram right, the light green wire should be for O/D, dark blue is power, and the other one is tcc. I think.......

Edit: Ooops. looked at the wrong year. Go here, do the hoop-jumping to get access, and have a look.

 

Okay, thank you. I'm familiar with BBB Industries, so I'm going to look that up when I get home tonight.

Before I start wiring the switches in, what is the consequence if I activate either or both at the wrong time? Obviously I know not to do it, I just want to know the full potential consequences if I bump the switch at the wrong moment or something.

 

For TCC, I think the worst that may happen is you stall the engine. For O/D though....... It likely depends on how fast your are going..... it's just another gear though, independent of the first three, so, it may act as a 'gear splitter', giving you what amounts to a six speed trans, (depending on ratios, or course.) Or, it may royally **** the transmission off, to the point that it turns itself into a grenade. I would highly recommend against experimenting with that though.

 

Yeah, I don't intend to, I'm just debating the utility of buying protected-cover switches that you can't accidentally flip.

What am I looking for on BBB? I'm not seeing anything related to the OD not working.

 

Pull up the wiring diagrams for the O/D control circuits, and then see if you can find where the problem is.

The PCM is setting any codes for no o/d?? Does your trans have the temp sensor on the cooler line?

 

There are no codes of any kind being thrown in relation to this issue. I can MAKE it throw one by unplugging the thing, but that's it.