Car: 1991 NA Automatic to S4 manual swap

So I am trying to wire the clutch interlock switch into the cars starting system. The car starts and runs fine with an idle around 750 RPM. There is a orange wire that was run by someone from the ignition switch (spliced with the B/R from the ignition and a Black/Blue wire that runs into the harness) to the engine bay where it is spliced back into the B/R wire that feeds the starter.

After I bit of research and learning about the ignition system I figured all I had to do was cut the orange wire and connect each end to the clutch interlock switch.

After I did this the car started only with the clutch in, which I wanted. However after driving for a bit I noticed my idle was high 1200 and every time I pushed the clutch in it would go down to 750 then when I released it reved to 2000 then settled at 1200. The check engine light also came on.

I unplugged the clutch switch and jumper it back to the way it was and next time I started the car the idle was back to 750 and the check engine light went off.

What I don't understand is why the car needs that wire to be continuous (clutch depressed fixes idle) to idle properly and not throw a code.

I'm trying to get it to start only with the clutch in, because it is part of the safety check they do at the dragway.

 

Does the Black/Blue wire run to the ignition switch and if so then this wire feeds the interlock w/voltage as the key is turned to start.

EDIT: Additionally, if you supply a wire to the interlock which has voltage w/key to ACC or on then when you press down on the clutch you are supplying voltage to the starter which engages w/the car running and up goes the rpm. If the interlock is supplied w/voltage "only" w/key to start then the starter will not be engaged when the car is running and the clutch depressed.

 

I'm not completely sure where the black/blue wire goes since it disappears into the massive wiring harness. It is spliced into the Black/red (starter signal wire) from the ignition switch along with the orange wire, so yes it comes from the ignition switch.

I guess I'll trace that black/blue wire as far as I can and see where it leads. Still if the orange wire is supplying the starter signal I thought that it would be the correct wire to go into the interlock switch.

 

What you need is a wire that supplies voltage to the starter w/key to start "only." What you have is a wire which has voltage w/key to on and when the engine is running and you depress the clutch the voltage is passed to the starter and it engages w/the car running which is wrong and the starter engaging w/the car running will add additional rpm to the engine and when you release the clutch the starter turns off and the rpm drops to normal levels. The Black/Blue wire should be the starter wire from the ignition and it "should not" be spliced to the other wire and is likely done so because the starter wire from the ignition probably does not work so a quick fix was done and thus the reason to not use the interlock.

 

The starter is not engaging in the on or acc position only when starting. The car idles properly (idle goes down from 1200 to 750) when the clutch is in (the orange wire has a free path from ignition switch to starter) and revs up when I release the clutch ( the orange wire is then open).

 

Check the voltage on the wire that leads from the interlock to the starter when the car is running and w/the clutch depressed and also not depressed.

Also, if wired incorrectly, the starter would not engage w/key to acc or on unless the clutch were depressed. So if the car was off and the key to on the starter would not engage if the clutch is not depressed.

And does the car have the BAC? This might be the problem.

 

Use the link provided to validate which switch you are working on.

Post #2.
https://www.rx7club.com/showthread.p...switch+picture

 

I'll check the voltage like you suggested.

I'm talking about the correct switch the one that's all the way up and is pushed down when the clutch pedal is depressed. I wired it back to the before configuration in my first post (bypasses interlock switch and starter cut relay) and it drove and idled fine.

The car has the BAC. Last time I checked it out it was fine according to the FSM.

The only time the car acted strangely is when i fed the orange wire through the interlock switch.

 

******So I am trying to wire the clutch interlock switch into the cars starting system. The car starts and runs fine with an idle around 750 RPM. There is a orange wire that was run by someone from the ignition switch (spliced with the B/R from the ignition and a Black/Blue wire that runs into the harness) to the engine bay where it is spliced back into the B/R wire that feeds the starter.****************************

Can you explain this just a little bit more.

Is the B/R wire you talk about at the ignition switch a wire that is a part of the pigtail of the ignition switch OR is it a wire in the connector on the front harness that connects to the ignition switches pigtail.

The ignition switch pigtail is: those wires soldered on the switch itself and whos other end is part of a connector, and that connector connects to a plug on the Front harness.

A jpg of the series five start circuit is attached. On that jpg the B/L wire is located on the plug that is part of the Front harness, not the ignition sw pigtail. That B/L wire goes to the starter cut relay located in the engine bay near the Main Relay.

The power passes thru that starter cut relay and goes to a B/G wire that connects to the clutch interlock switch. Your car has a B/G wire leaving the circuit opening relay, but on your automatic car it went a inhibitor switch plug. I don't KNOW where that inhibitor sw is on a automatic car. I guess on the transmission that ain't thar no 'mo. But the connector should still be there ....down there somewhere.

So the power left the inhibitor sw and went on to the starter solenoid and also to other items like the circuit opening relay and a wire on the ECU that lets the ECU know your starting the car and also to the heater blower assy.

So I've had time to think about this while typing. Question: Did you unplug the ECAT computer or remove the unit itself???? That might have something to do with it...maybe.

Guessing.

 

I have that 1991 RX7 wiring diagram book where you got the diagrams. I'm still confused which wire the Black/Blue one is/

The B/R wire is soldered (part of) on to the ignition switch itself and ends at a plug just under the dash. It plugs into a Black/blue wire (B/L?) which shortly after the plug is spliced into the orange wire. I'm not sure where the hell that black/blue wire goes (disappears into wiring harness mess). Then in the engine bay the orange wire comes out of the fire wall and splices into a B/R wire again before a plug which houses both that same B/R wire and a B/G wire. The color of the stater signal wire is B/R (99% sure). I see the interlock switch which is currently unplugged is B/G and one of the 3 wires running to the starter cut relay is B/G.

I took some pictures but the quality isn't great. Never the less they might help.

 

The starter wire from the ignition (front harness) will have voltage w/key to start. If the wire which provides voltage to the interlock has voltage w/key to on as an example then it is not the proper wire to use. If the B/L wire were by itself (not spliced) then it would have voltage w/key to on. You can tell where it goes to by how it behaves voltage wise as opposed to visual inspection alone.

 

I need to get down and dirty with the multimeter and check the B/L wire but it should only get voltage when turned to start.

The B/L wire is plugged into the starter wire B/R coming form the ignition so it should only get voltage when the car is turned to start. What I've gathered so far is that the orange wire is spliced into the B/L and goes to the B/R wire in the engine bay that feeds the starter when the key is turned to start. This was done to bypass the starter cut relay and interlock switch.

This still doesn't explain why when I cut the orange wire in half and connect each side to the interlock switch the car acts up, since it should only get voltage when the ignition is turned to start and it shouldn't need to be continuous except when starting the car.

 

In my last post I began by saying the B/L wire would only have power w/key to start and then followed that up by contradicting myself due to a typo but you are right to state that it should only have voltage w/key to start.

 

In looking at the S5 wiring diagram there is but one B/R wire and it is for the IG2 fuses in the interior fuse box which supplies these fuses w/voltage "w/key to on." Since your car "was an automatic," the wiring colors might differ some as compared to the FSM schematic provided, but if not then the B/R wire coming from the front harness ignition switch connector "is not a wire that has voltage w/key to start."

 

Yeah the FSM diagram doesn't label the color of the wires coming of the ignition switch. The B/R wire coming off the ignition switch connects to the B/L wire. I think the (-( symbol in the diagram denotes the plug that connects the B/R to B/L. This is the one with voltage when the key is turned to start.

 

Usually when referring to the ignition wires it is viewed from the "front harness" side of the connector and in reading your initial posts it came across as you were referencing the same wires from the front harness, but apparently not thus the confusion.

So to clarify, the Orange wire that taps into the ignition wire is tapped into the B/R wire that is soldered to the ignition switch and not tapped into the B/L wire. Correct?

 

All 3 are connected. The B/R is soldered into/part of the ignition switch and then plugs into the B/L wire. The orange wire is spliced into the B/L wire right after the plug. So basically the B/R from the ignition splits into the orange and B/L wire.

EDIT: in post #10 the middle picture is the junction I'm talking about. The black plug is the B/R wire that goes to the blue connector that the orange and B/L wire come out of.

 

Even though the Starter Cut relay was bypassed is it still in the engine bay next to the Main relay or was it removed?

 

It is there and plugged in. the picture all the way to the right in post # 10 shows the wires running into it one of which is B/G

 

If I had that car and it was a series five automatic and I had put a manual in it along with a clutch interlock switch that I wanted to work.............................................. ...I'd cut that orange wire off and set it aside. Then you know the start wire that is Black with a Blue stripe goes to the starter cut relay and that power will pass thru that relay and come out and now go to the INHIBITOR SWITCH that should still exist on the harness...somewhere.

I'd find that plug which is shown in the second jpg attached. I'd splice a new wire to the Black/Green wire in that plug and run that wire to one of the clutch interlock switch wires.

Then the other wire on the clutch interlock switch .....I'd splice a new wire to it and run it to the INHIBITOR SWITCH and connect it to the B/R wire in that plug.

The car should now start if the clutch pedal is depressed and all should be well.

Did you remove the automatich transmissions computer?????? Not the ECU but the ECAT computer????????

The attached jpg kinda show what I'm talking about. Or tries to a bit.

Is the automatic trans Inhibitor Switch being used in any of your pictures????

First jpg is to just confuse things..humor

 

If I understand this correctly you'd basically just wire the clutch interlock switch as if it were the inhibitor switch and bypass the inhibitor. (B/G from relay -> interlock in -> interlock out -> B/R starter wire) I'll give this a try. From my research I think the inhibitor plug is suppose to be located near the shifter.

I still haven't checked on the auto computer and don't have the inhibitor pictured.

 

So I want to update this thread with my resolution in case anyone experiences a similar problem.

I finally got some time to work on this again and got everything fixed. I ran a wire from the inhibitor plug B/G to the clutch switch and from the clutch switch back to the B/R on the inhibitor switch. After doing this the car still behaved strangely as I explained in other posts. This was because the EC-AT was still plugged in. I had assumed that when the car was swapped the person doing the swap would have already unplugged it. This cured the reving when releasing the clutch issue.

It also had a negative effect on my idle. I had set the idle to 750 rpm before touching the wiring. After rewiring and unplugging the EC-AT I adjusted the throttle cable, TPS, and Idle control screw. (Before rewiring and unplugging the AC-ET, the idle screw never effected my idle) It took a few tries but the car idles at 750 rpm and idles more smoothly then before. The hold light no longer flashes since unplugging the EC-AT which makes sense. The car also feels like it has more power.

The only negative thing that I can't figure out is when cruising at a steady speed, in the lower rpms, with constant gas pedal pressure the car will buck very slightly.

 

Bump... need to refer back to this thread while trouble shooting.