Twilight Sentinel and Auto Air on '93 Wagon

[bocoogto]

A local salvage yard has two '92 and one '93 Roadmasters with Twilight Sentinels and Auto Air. My '93 wagon has neither. How many parts need to be changed to add either option to my car? I've noticed my '93 has a hole next to the radio speaker grille for the light sensor.

The cost of parts would be minimal--probably $35.

[rdmaster92]

I can help a little bit I think. My '92 had problems with the Twilight Sentinel. The lights would work for a while driving at night, then the dash lights went out. It was not until someone flashed their lights from behind (why would they expect I would notice?) that I thought the dash lights might not be the only things out. I found that the headlights stayed on, but side marker and parking lights were out completely. Brake lights worked though. Lights worked fine when using rocker switch. I only mention this story, because it gave me an education in the components of the Twilight Sentinel in my '92 RMW.

I tried replacing the rotary switch first, to no avail. By the way, switches are same as Caprice thru '93. The whole 3-switch assembly interchanges from Caprice to RdMaster, but the face of the switch set is gray on Caprice, and Caprice lacks markings on the rocker (or is it other way around?). Each individual switch is replaceable. It seems the next step was to replace the Twilight Sentinel module. Even with a Roadmaster shop manual, this peice is difficult to identify and locate. It turns out that the module is way up under the dash, right next to the steering column, to the passenger side, near the firewall. One module was off-white, the other was gray. Module slides off of a bracket, which is bolted on under the dash. It has 2 connectors, both 8-way, but one smaller than the other. If I can find one of my modules, I'll snap a shot and post it.

Anyway, as you guessed, you need the sensor at the vent. You also need the rotary switch and the Twilight Sentinel module. I think there are some differences in the wiring harnesses under the dash, so it might be a good idea to secure some harnesses from the donor vehicle.

After I went to the trouble of getting mine to work again, I noted that the system was not relatively complex, and thought it could be adapted to my '69 Skylark. Essentially the TS module has 2 relays, one which switches the headlights, the other which switches the dash lights, side markers, and tail lights (this second relay I am assuming was bad on my module). I decided that I would get another module, rotary switch, and sensor to make the system work in my old car.

Sadly, 1 week (early May) after I got the TS to work again, the tranny in my wagon developed problems, not wanting to shift above 2nd gear, in Omaha, 200 miles from home. I had just put my house in Omaha on the market, and received a quick offer, wanting to close at the end of May. I guess it isn't all sad news, but the unfortunate result is that it would cost more to repair the car than the car was worth, it would cost too much to transport the car, and I didn't have time to deal with the car and the sale of the home. Sadly, I was forced to make a decision to sell the car to a salvage yard in Omaha for $320. But, I was determined to have those parts to upgrade my Skylark, so was determined to rob the car of it's twilight sentinel before driving the car (yes it still ran fairly good) to the salvage yard. As I didn't want to pay for a tow, I carefully cut parts of the wiring harness to remove the TS components and connectors, while leaving the rest of the wiring reasonably intact. The sensor wiring pulled pretty easily down through the dash, leaving the wire intact to the harness I snipped out. I think cutting the big yellow wire, though, caused the headlights and parklights not to work (there was a splice to add the TS in the harness, with part of the wire connecting to the normal rocker switch). No matter, as it was daylight anyway.

Anyway, thats my long-winded story. I think what you want to do can be done, with some work and thought. As I mentioned before, I would take the time to get a complete un-hacked harness from the TS donor vehicle. If nothing else, you could disassemble the harness to see how GM worked everything together.

I wish you the best of luck!!

[rdmaster92]

Hmmmm. Just noticed you asked about swapping in the auto air option as well. It has been a long time since I dealt with that system. I replaced a blower control module (needlessly) that was specific to the auto air conditioning (aka option C68). I ended up replacing the control head (the one with the AC user interface, or controls) to fix my problem. I peeked at my shop manual, and it seems there may be a lot of systems integrated with it. It seems there are different sections for electrical diagnosis based on whether you have manual AC (C60) or auto AC (C68). Some particular areas are the heated mirrors/defroster, blower motor circuits, and air delivery circuits. It seems there would be a lot of differences between the two sytems and I would assume changing over would be pretty difficult. I don't think it is something one would want to attempt without a shop manual. In fact, even if I still had my RM, I would be scared to try even with the manual.