I would like to terminate some wires in the engine bay and re-route them from my MS through at different grommet to the engine.

I would like to do this to...

The TPS, IAC and Water Temp connection that's on the thermostat area.

The only problem is I have no idea which PINs on the harness I need to wire the new wires/sensors to.

Can someone help me out?



Also, the water temp one is a single wire black/green stripe. But if I follow it a bit further I see that it splits into 3 wires, all the same black/green stripe. Where do these run to? Why are there 3 wires?

 

http://www.madracki.com/miata/images/wiring/91diag.pdf

 

Hmm..

I don't see a TPS, IAC or Water Temp sensor in that PDF....

 

I believe they are all direct

 

OK cool...

Can anyone else confirm that? Since he is'nt 100%, I'd like a confirm/deny before I go start chopping wires.

 

for TPS
1N goes to 5vref
2L goes to VTPS signal IN
2C goes to ground

For AIT

2P goes to singal wire for AIT
2C goes to sensor ground wire

For Coolant
unknow still need help (this the the FRONT coolant sensor)

For IAC
unknown still need help for this

 

both are in the link

IIRC the front coolant sensor is for the A/C

 

On a 90-93, the front clt sensor (in the thermostat housing) drives the cooling fan. It does not hit the ECU.

 

Ok, thanks. I guess I'll go trace that one back then.

 

Is this the fan relay? It was located next to the clutch slave behind a black box. It's the only relay I can find. If it is, I guess I could find out which one goes to the coolant and wire from the relay direct to the sensor?

 

I've read now too, that you can have the MS control the fans? Since I will be doing a coolant re route in a few weeks when the new engine goes in and I put a freeze plug in the front neck area. If I can have the MS control it, I can just remove the sensor completly? How does that sound?

 

This is my current MSQ and it looks like it is already set up for clt output but I'm not using it?



Can I use this output (2) as a control for the fan relay? So instead of the ground coming from the sensor, I would assume all this pin is, is a ground? And goes on when the MS sees the set temp? Now here's the question. What pin is the output for this (output 2/JS3)?


According to the Wiring Diagram also posted in this thread, the shared ground that goes to the sensor on the front is already connected to the ECU at PIN 1R. Could I just move the wire from 1R to whichever PIN the JS3 output is, remove the sensor and call it a day? The MS gets it's temp from the coolant temp sensor on the back of the cyl head does it not?

 

anyone? I want to get my car back and running so I can drive to work again :P

 

bump

 

Huh, looks like you're right. I'd totally forgotten that that wire branched back to the ECU.

Yeah, just go ahead and do a relay driver mod in your MS and connect it to 1R.

 

So if I'm getting this right... All I have to do is wire the black/green ground that's currently going to 1R to the JS3 ouput (still haven't figured out which one this is) and it will work?

Are the JS outputs ground or 12v?

I just did a search on "relay driver mod" and couldn't find anything. Can you point me in the right direction?

 

You already have the relay driver mod in your megasquirt and it should already be driving your fan relay based on how I built your harness. You should be able to remove the front temp sensor without any issue.

 

Ahh, interesting. I will go warm my car up then and see if the fan switches on.

 

It should work unless you've done some mucking around in your settings and changed it.

 

No I haven't. I did cut off the thermoswitch sensor clip though. With all this research of trying to figure this out I never really thought to see if it was hooked up this way already.

I'm going to wait till the garage warms up a bit. I woke up to snow this morning so its a bit nippy outside.