Gtfour st185 wiring harness removal

Boosted185

New member
Was wondering if anyone had a decent diagram of the harness and where it runs inside the car, not exactly sure what I should be taking out Or leaving in so I’d rather be safe then sorry
 

Magroo

New member
Best advice I can give you is start at the relay/fuse box next to the battery.

Pop the bottom cover off and unplug 2 connectors. I think one is white and the other off white.

Unplug starter, coolant temp stuff, Cruise control, remove diagnostic port, and unplug distributor, ignitor and coil.

Unbolt fuel rail and the harness from the intake manifold.

From there it's stuff like pressure sensor, ac idle up, egr, tps, idle air control valve.

Then move over to the ac compressor, alternator , and radiator temp sensor. Peel all that back.

From there it's just the bulkhead connector and 2 grey connectors near the AC lines at the firewall. Inside the car need to unplug the ecu and it should come right out.

Search for the bgb on one of the Celica forums. I forget which one had pics of the layout.

Edit. Going from memory you have to remove the alternator to get to the piece that runs between the timing cover and valve cover. It's also bolts in 1 or 2 places.
 

Boosted185

New member
Engine side was easy enough but I’m wondering about under the dash. Basically what I’m confused about is where it goes once it comes through the fire wall. I didn’t wanna start ripping anything about so I just took the glove box out and it almost looks like it comes through the fire wall but then back out again to my turbo pressure sensor, not sure if that’s part of it. Some weird Japanese security system was installed so I have a cluster of wire on drivers side which doesn’t help
 
It's not clear to me exactly what you need. Could you be very specific about what it is you need?

At a high level, the wiring system is made up of multiple individual harnesses that make up the wiring network in a car. And of course some wires come into the cabin (for a reason) and then are routed back towards where they originated (as the control part of a specific item may be within the cabin). Are you looking only for how the wiring for your manifold pressure sensor is routed?
 

fussellbug

New member
On the USDM Celica, the harness comes through the right hand (passenger) side of the firewall, behind the glovebox and over to the ECU under the central part of the dashboard, directly forward of the shifter. There are harness plugs that go directly into the ECU and two others adjacent to the ECU that plug into another harness.

On the JDM models, the harness will pass through the left hand (passenger) side of the firewall and also run toward the center of the car to connect to the ECU and a few adjacent plugs.
 
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