Stock FC Wiring Removal

infernosg · 05-10-2011, 01:30 PM

I guess this fits best here as I'm dealing with a S5 N/A RX-7.

I want to remove any wires, connectors, computers that won't be used for my build. I'm planning on running an aftermarket ECU with a custom harness but I want to retain stock dash functionality. Items to be removed include anything associated with stock engine control, A/C, P/S, foglights theft-deterrence and emissions (did I forget anything?). I have a FSM and the "emission" or EM harness seems straightforward as to what can be removed and the "engine" (E) harness needs to stay intact as it comprises the main power system. That leaves the "front" (F) harness...

I'm trying to figure out how to go about removing the extraneous wires. Is it a matter of finding the connector to be removed and following its wire(s) back to the source (ECU) and removing them? Since the ECU is being removed can I remove any wire going to its connectors? How could this affect the chassis systems? I know new fuel pump wiring will be needed but will I lose my lights, fan, etc. by removing the ECU? For grounds it looks like most have to stay but maybe a few can be removed. What about the anti-theft system? Supposedly it's integral to the CPU but can it be disabled/removed without immobilizing the car?

Most importantly, is it possible to do any of this without removing the dash? The last time I did anything with the dash I had plastic breaking just by looking at it.

EDIT: So it doesn't look like it's possible to remove the anti-theft system from the S5's without disabling some other systems in the process as it's part of the CPU.

Also, could a mod fix the title? Should be "Stock FC Wiring Removal" or "Stock Wiring Removal".

NoDOHC · 05-10-2011, 09:13 PM

I know that you can remove the power steering computer with no ill effects.

The CPU controls the warning lights, etc. so you will want to keep it.

The ECU can be removed without hurting anything (as long as you replace it with an aftermarket one).

You will probably want to replace the Circuit opening relay with a much simpler design so that you don't have to worry about the AFM switch for the fuel pump (just control it with the ECU).

You will need to keep the existing alternator wiring, I don't know if it is worth going through the harness to remove all the A/C related wiring.

infernosg · 05-11-2011, 08:00 AM

Quote:

Originally Posted by NoDOHC

You will probably want to replace the Circuit opening relay with a much simpler design so that you don't have to worry about the AFM switch for the fuel pump (just control it with the ECU).

Can you elaborate on this? If I understand correctly the ECU I want to use is capable of driving a fuel pump (fused and relay). So I can bypass both the circuit opening relay (connection F-08 under dash) and the fuel pump relay and resistor (F-60 behind bumper cover)?

I plan on keeping the stock charing system wires in place for now. I am relocating the battery to the back so I'm either running the stock wires to a circuit breaker or fuse, which then leads back to the battery, or end up replacing all those wires in the process.

My main goal is just to get rid of things I really don't need. Things like the check connectors and AAS wires and computer for example. I removed the ECU and emissions harness last night and I'm in the process of isolating the wiper and temperature wires so they are retained.

RETed · 05-11-2011, 09:44 AM

Quote:

Originally Posted by infernosg

Also, could a mod fix the title? Should be "Stock FC Wiring Removal" or "Stock Wiring Removal".

Done.

-Ted

infernosg · 05-12-2011, 08:12 AM

Thanks Ted.

I've come to realize the Wiring Diagram in the 1989 FSM is more a guideline than accurate description of what's actually on the car. So far two blatant errors found include the wiper motor wiring, which the FSM says connects the FEM-01 but is really FEM-02 (big difference), and the theft-deterrence system, which the FSM states is both integral to the CPU (true for S5) and being a separate module behind the glovebox (true for S4). It's like the Wiring Diagram is an odd mix of S4 and S5 schematics.

I've stripped the emissions (EM) harness down to just the wiper motor and dash temperature gauge sender wires but I'm concerned about one thing. By do so, I deleted two grounds from the system (8 and 9). According to the FSM the "Passive Shoulder Belt System", part of the front (F) harness, actually interfaces with the emissions harness and utilizes ground point #9. There is another, dedicated ground for the seat belt system (1) but I'm concerned this may cause something not to work properly.

05-10-2011, 01:30 PM	#1
infernosg IT'S ALIVE! Join Date: Dec 2009 Location: Richmond, VA iTrader: (5) Posts: 811 Rep Power: 15	Stock FC Wiring Removal I guess this fits best here as I'm dealing with a S5 N/A RX-7. I want to remove any wires, connectors, computers that won't be used for my build. I'm planning on running an aftermarket ECU with a custom harness but I want to retain stock dash functionality. Items to be removed include anything associated with stock engine control, A/C, P/S, foglights theft-deterrence and emissions (did I forget anything?). I have a FSM and the "emission" or EM harness seems straightforward as to what can be removed and the "engine" (E) harness needs to stay intact as it comprises the main power system. That leaves the "front" (F) harness... I'm trying to figure out how to go about removing the extraneous wires. Is it a matter of finding the connector to be removed and following its wire(s) back to the source (ECU) and removing them? Since the ECU is being removed can I remove any wire going to its connectors? How could this affect the chassis systems? I know new fuel pump wiring will be needed but will I lose my lights, fan, etc. by removing the ECU? For grounds it looks like most have to stay but maybe a few can be removed. What about the anti-theft system? Supposedly it's integral to the CPU but can it be disabled/removed without immobilizing the car? Most importantly, is it possible to do any of this without removing the dash? The last time I did anything with the dash I had plastic breaking just by looking at it. EDIT: So it doesn't look like it's possible to remove the anti-theft system from the S5's without disabling some other systems in the process as it's part of the CPU. Also, could a mod fix the title? Should be "Stock FC Wiring Removal" or "Stock Wiring Removal". __________________ '86 Mazda RX-7 Base '79 Mazda RX-7 GS Last edited by infernosg; 05-10-2011 at 03:42 PM..

05-10-2011, 09:13 PM	#2
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin iTrader: (1) Posts: 855 Rep Power: 17	I know that you can remove the power steering computer with no ill effects. The CPU controls the warning lights, etc. so you will want to keep it. The ECU can be removed without hurting anything (as long as you replace it with an aftermarket one). You will probably want to replace the Circuit opening relay with a much simpler design so that you don't have to worry about the AFM switch for the fuel pump (just control it with the ECU). You will need to keep the existing alternator wiring, I don't know if it is worth going through the harness to remove all the A/C related wiring. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

05-12-2011, 08:12 AM	#5
infernosg IT'S ALIVE! Join Date: Dec 2009 Location: Richmond, VA iTrader: (5) Posts: 811 Rep Power: 15	Thanks Ted. I've come to realize the Wiring Diagram in the 1989 FSM is more a guideline than accurate description of what's actually on the car. So far two blatant errors found include the wiper motor wiring, which the FSM says connects the FEM-01 but is really FEM-02 (big difference), and the theft-deterrence system, which the FSM states is both integral to the CPU (true for S5) and being a separate module behind the glovebox (true for S4). It's like the Wiring Diagram is an odd mix of S4 and S5 schematics. I've stripped the emissions (EM) harness down to just the wiper motor and dash temperature gauge sender wires but I'm concerned about one thing. By do so, I deleted two grounds from the system (8 and 9). According to the FSM the "Passive Shoulder Belt System", part of the front (F) harness, actually interfaces with the emissions harness and utilizes ground point #9. There is another, dedicated ground for the seat belt system (1) but I'm concerned this may cause something not to work properly. __________________ '86 Mazda RX-7 Base '79 Mazda RX-7 GS

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