1G changing wiring harness. question about one connector

[3kgt2nv]

Howdy all, I need some help on this one.

I have a 90 gsx with manual trans and no abs or alarm and i am switching my engine room harness to a 92 awd no abs or alarm harness and there is one connector that I don't know what its to.

It is under the drivers side fender that plugs in near the fuse block.

In the following picture I have the plug in question circled and a close up of the connector. I have the connectors numbered to line up with the 90 harness which is the third pic.

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the connector in question

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stock 90 harness

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I tried digging thru the fsm but have been unable to locate the plug and this is one of the last roadblocks to getting the car started after a lengthy rebuild.

thanks for the help.

 

[19Eclipse90]

The four pin plug goes to the IOD (ignition-off-draw) Connector which is in the '92+ main engine bay fuse box; it connects to the front of a '92+ junction block. Through fuse 4 (10A, RADIO), the two blue wires are involved with the radio and antenna motor (if so equipped).

Through fuse 19 (10A, ROOM), the two red wires are involved with the TCU, dome light, door-ajar warning light, ignition key light, luggage compartment light, ECU, radio, ABS relay, motor antenna, seat belt control unit, ABS control unit, and door lock control unit, when applicable.

In short, running lights: no.

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[3kgt2nv]

since its just for ignition off draw is it possible to just leave it unplugged at the risk of loosing interior lights and other power off features or will this kill the ecu to lose this. I can always grab the distribution block out of the same 92 gsx if i absolutely have to run it to protect the ecu. If I have to but then i might run into an issue with the interior harnesses also. Should I also just grab all the wiring harness out of the car to be safe? the under dash and the interior harness to the tail lights/ rear portion of the car?

 

[19Eclipse90]

Honestly, I'm not completely sure that the engine will work leaving that unplugged, without any other modification.

In a purely '92+ vehicle and unplugged, the ECU will not have voltage at ECU pin 103. Steve's posts are always good reference materials for this sort of stuff, and maybe he'll chime in with a suggestion to this as well.

http://www.dsmtuners.com/forums/articles-tuning-ecu/435961-1g-basic-ecu-mpi-circuit-function.html
http://www.dsmtuners.com/forums/electrical-tech/431887-1g-ecu-wont-power-up.html#post152934600
http://www.dsmtuners.com/forums/newbie-forum/422425-no-power-pin-103-ecu.html#post152825747

Since the junction blocks are different, the wiring is routed differently. In a '90-'91, voltage travels through fuse 19 in the junction block, and to ECU pin 103. In a '92+, it goes through fuse 19, to the IOD connector, back to the junction block, to ECU pin 103.

I'm sure there's ways to "bypass" all that IOD stuff for that ('90) harness and maintain power to pin 103 without switching junction blocks. The easiest looks like it would be running a wire from the non-hot side of fuse 19 (or perhaps a pigtail fuse) to ECU pin 103. I've never messed with anything like that so that's putting two and two together between the different diagrams and making it as simple as possible.

Changing harnesses isn't fun but would be practically fool-proof.

 

[3kgt2nv]

since im stuck at work and cant access caps can someone post up the part numbers for the 90 interior harness and the 92 interior harness just to see if they are the same or if they will need to be swapped.

Thanks

 

[19Eclipse90]

On the USDM 1G 2.0L FWD models alone, there are 16 different body harnesses for different options, body and transaxle types, etc.

In any case, the '90 is different enough. As mentioned, the junction blocks are very different and the body harness is very involved with that; the engine control harnesses are different and those connect to the body harness as well. Personally, I think it'd be easier to swap them all instead of trying to piece a couple together with the '90.

Here's what I was thinking for the "bypass", if you were still interested. C-41 is the connector that plugs into the '92+ junction block. It appears to me that if a wire (the blue line) would run directly from the #19 fuse to the ECU pin 63, you'd effectively have workable harness for the '90 or '91 junction block. If anyone can explain to me why this wouldn't work, I'd love to hear it.

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[3kgt2nv]

Im thinking tomorrow i am pulling all the harnesses out of the 92 gsx and just swapping them all so i know for a fact that it will work

edit. 3.5 hours later i now have all 92 harness out of the car at the junkyard.