View Full Version : My wife thinks I'm a giant winner

02-13-2011, 10:03 PM
So my white 91 GT-S is rotting out from under me (floor pans, frame rail, rockers, the usual) and this past fall I took ownership of a red 90 GT with an excellent body (very, very rare here in the land of salt and rust) but a hacked wiring harness from previous alarm/remote start disasters. It's so bad it drains the battery in roughly six hours. But I got the car for free so...


So being the huge winner I am, and needing my daily driver on the road, I picked-up a black 91 GT-S for peanuts as a donor car. I'll be swapping the engine, transmission, and wiring harness over.

I am inclined to swap the in-dash wiring loom at the same time, in order to eliminate the wiring nightmares under the steering column where the alarm brain is. My question is this: The dash controls (heat, fan speeds, vent selection) are all different between the GT and the GT-S...once the dash is completely dismantled, is it fairly simple to separate this portion (under-dash) of the wiring loom from the portions running to the doors and to the rear of the vehicle? I'd rather not be soldering new connections for the next month.

Any advice or related experience would be most appreciated. :beerchug:

And mods, please feel free to move this to the electrical forum...I don't know why I posted in 5th gen, I meant it for the proper forum...sorry.

02-13-2011, 11:40 PM
I'm thinking the wire looms in both cars would be the same. It's just that some of the connections will not be needed and can be taped out of the way. They pretty much try to build one wire harness that can work in all of the same generation of a particular model. It's cheaper and quicker for auto makers to do that.

Also, this thread is fine being in the 5th gen forum.

02-13-2011, 11:57 PM
If the 91 GT-S controls are different, I would bet on them being the updated electronic/automatic HVAC controls. In that case, why not swap those over as well as the wiring?

02-14-2011, 12:17 AM
You will run into problems is one car has automatic climate control vs. manual climate control. That damn auto button means there has to be a sensor someplace for temp, a relay and wiring to accommodate the different control. Otherwise, everything swaps over without issue.

I was going to swap my auto-climate control from my 92' GTS donor to my 91' GTS without. I didn't move everything, and now have to search for the correct wiring to make it work. I thought the controls were swappable like almost everything else. Whoops.

02-14-2011, 02:00 AM
Yeah, I think I'll swap the controls over with the wiring... the controls are different but both the GT and the GT-S's have the automatic-style heat controls (rheostat-control, uses the round knob to switch from cold to hot) and the push-button vent controls. I'll take pics when I get back outside...Hookecho, I really you're right about the standardized wiring loom between trim levels...it would save me a LOT of hassle.

Other swap-over items (no surprises here): front fenders/inner fenders, rear disc brakes plus proportioning valve, and the System 10 components (door subs and panels, floor-mounted amp). This should be the fun-est spring in a long time, barring disaster...unfortunately my wife's patience has run low, and she's now demanding that I agree to installing one lawn gnome on our property for each car I have. I hate lawn gnomes, but I guess it's a small price to pay.

02-14-2011, 02:15 AM
why not use the black GTS?

02-14-2011, 02:52 AM
My wire loom differed drastically between the 92' GTS and the 91' GTS when it came to climate controls. I was missing a couple plugs that I could not find. I assume the mid generation upgrades were responsible for the changes.

02-14-2011, 06:05 AM
why not use the black GTS?

Um, unfortunately I really meant it when I said the red GT's clean body is rare here...the black GT-S has bongo for rockers and holes around the rear wheel wells. My heart just aches from watching the rust consume my white GT-S for the past three years (it was too far gone to be worth fixing even when I bought it). I hate body work and I just want a clean project car (yeah, I'm so original, I want to do the 3SGTE swap next year). And that is why the black GT-S won't do... unfortunately.

02-14-2011, 06:23 AM
My wire loom differed drastically between the 92' GTS and the 91' GTS when it came to climate controls. I was missing a couple plugs that I could not find. I assume the mid generation upgrades were responsible for the changes.

Well I know there were a ton of production changes between the 90-91 runs and the 92-93 runs...really the GT and the GT-S have the same type of controls, but the finish is different. The first pic below is the GT dash controls (note the fan speeds are on an ugly knob similar to the heat mixture controls):


And here as you will almost all recognize is the completely different GT-S dash (with push-button fan speeds, unlike the GT, and with a different style heat mixture control knob):


Aside from these differences, the gauge cluster is different too, and I hate the GT gauges (see below):


I much prefer the GT-S gauges, they're more pleasing to the eye at a glance and they include the voltmeter to tip me off when my alternator is about to catch fire (which they do about once a year):


02-14-2011, 08:16 AM
The thermister you're looking for at least I know where to find -- the passenger-side dash, right by the windshield.

02-14-2011, 08:34 AM
My pod has a giant auto button and a knob that you set to temperatures read in fahrenheit. No red / blue mixture. You're missing an AC button!

02-17-2011, 01:52 AM
Your GT-S is one of the first I have seen without automatic climate control. You do not have auto climate control, just the refreshed standard module. Changing them over could be a pain as the wiring harness' differed after the refresh.

The automatic climate control unit looks like this:


Another way you can tell if you have the automatic climate control is the rear of the climate control unit. If there in a cable physically attached to the rear of the module that connects to the coolant regulator in the engine compartment, you have manual climate control. The automatic climate control unit has plugs only, no cable the physically attaches to the rear of the unit (although there still is a cable inside the engine bayP.

Converting a non-automatic climate control Celica into an automatic climate control Celica would be a nightmare. There are two sensors inside the car that need to be wired, a couple extra sensors in the engine compartment and god knows what else. Basically you need a new wiring harness. Save yourself the hassle.