MtnRacer

Has anyone ever had to replace the entire CPU harness? How involved of a job is that(ie: how many hours)? Similar to pulling the ECU harness? What other wiring harnesses exist on the car, if any? Thanks guys.

Steve

hIGGI

iTrader: (7)

u dont want to replace in car harness which is under dash...its shitload of wires, look at pictures of our cars :

http://rx7cz.net/photos/

AbecX

Doesnt look as bad as I thought it would. I'm about to undertake the same endeavor.

DaleClark

iTrader: (55)

The front part of the car really has 3 harnesses -

- The ECU harness on the passenger side of the car
- The main harness on the driver's side of the car
- The starting/charging harness on the driver's side.

The starting/charging harness is relatively simple - it has the alternator plug, the battery terminals, the starter terminals, etc. It plugs into the main harness.

The main harness is a BITCH - I pulled one from a car once, and that was enough for me. It starts at the passenger side headlight, goes along the nose of the car, back to the firewall, and all under the dash. The fuse box unde the dash is built into it.

You'd have to have a REALLY good reason to pull the main harness. Probably better to repair or bypass parts of the harness that might be damaged.

Dale

banzaitoyota

Or you or changing a S4 body to S5 engine, and you want a factory style installation, Why I don't know.

cblake3

iTrader: (2)

I just finished replacing my "Front Harness". This is what the main harness is reffered to in the factory manual. I unfortunately had a short in the old harness that melted the insulation off of several of the wires in this harness. It was very labor intensive.
It involved labeling every single plug in the harness and the removal of the following peices:
Passenger seat
Entire dash
center counsole
steering wheel
dead pedal
door sill trim
Heater core and related HVAC equipment
Main egi relay
Trailing coil
Battery and assembly
fan shroud
fan
AFM/TID
headlight trim

It took a long time to do, but I can thankfully say that the car is up and running!
Let me know if you need help.
Take pics to refer to when reassembling.
Good luck!

MtnRacer

I'm considering the possibility of converting an auto to a 5spd, and rather than hack up wires, I just might replace the whol CPU harness with the TII harness in my donor car. That way, I should have the proper leads and connectors for my 5spd tranny going into the AutoTranny body. I'm kind of a perfection nut, so I don't mind getting my hands dirty to do it right. I do mind screwing up my harness in the car and not being able to put it back together, so I thought I'd find out how difficult it was. Approximately how long did it take you guys to pull it? With or without help? Using the FSM I assume? Thanks!

Steve

Silkworm

Yes, I've done it, I'ts a freaking pain in the ***!

cblake gives a good description of what you have to do, basically that harness runs all the way down the drivers side of the engine bay, down behind the radiator accross to the other side, and ends at the passenger headlight. From inside it runs from the fusebox, over the steering column mount, down along the firewall over to the ECU and some other wires for the hvac/window/etc.

It's not fun.

The fusebox is held in by a bolt, and a clip. Be careful removing the fusebox, the clip holds on really well, and I ended up almost breaking the metal bracket the clip snags on.

PaulC

AreExSeven

I've got a brand new front harness for a S5 TII if anyone wants to buy one

MtnRacer

Just to make sure, I'm correct in assuming that the an Auto CPU harness differs from a 5spd CPU harness, correct? 0 =) ...and this would solve my problems? lol, I haven't even bought the auto chassis yet, and I've already got a headache. should be a REALLY fun project and great learning experience though.

Steve

AbecX

if your doing a t2 swap in a n/a, dont you just have to replace the ECU harness

MtnRacer

lol, well yeah, but I'm not worried about that part, just the CPU harness. If it were a TII swap into a 5spd chassis, it'd be a little easier, but since the chassis may be an auto, I'm concerned with getting everything hooked up correctly as far as the transmission goes. I think that since I'm already going to have the dash pulled apart for other reasons, this is going to be a little easier than it might be otherwise. We'll see.

Steve

P.S. I'm off for Seven Stock!! See some of you guys there! Take care!

Silkworm

Yes, but not drastically IIRC.

The big one is the wiring for the alternator, it's wired differently in the auto (routes out through the Emissions side of the harness), and that wiring blocks the ECU signal for boost pressure going to the guage cluster, again, IIRC. I ran into these issues while troubleshooting my ITS car with the alternator wiring not existing (using the auto Front harness and a manual emission harness.

PaulC

AbecX

So if since I have a 5spd n/a 1986 Rx7, what all do I need to get wiring harness wise, just the ecu and knock sensor stuff?

banzaitoyota

I thought you also needed the main harness so the warning lights and dash cluster will function right. (Please correct me if I am mistaken)

Silkworm

Abec, not sure what you're talking about, I don't think Mtn was talking about an NA to Turbo swap..

Well, on my NA, running an auto front harness, my warning lights and dash cluster function ok.

PaulC

DaleClark

iTrader: (55)

Actually, the transmission wiring is on the charging harness, which is separate from the main harness. At least that's the case on my '88 Turbo. This would actually be quite easy to swap out, or to remove the harness, modify it, and put it back in the car.

Under the brake master cylinder are a number of connectors - these are the "jumper" connectors that go between the main and charging harness for the tranny wiring, the oil level sensor wiring, etc.

Dale

Silkworm

However Dale, it isn't always on the same harness, depending on the version of the car, which is precisely why I had so damn much trouble.

PaulC

hIGGI

iTrader: (7)

i have gone thru converting euro NA with distributor to one with CAS and it was enought for me..

why can`t we have wireless cars ? :o))

MtnRacer

I'm sorry, Dale, Paul, I think I missed something in your dialogue... The tranny wires are on the charging harness(that's the third harness right? in addition to the main and ECU harness?), but the starter wiring is different on an auto CPU or ECU harness?

Just to clarify, this would be an automatic GTU that I would be putting a TII engine and tranny in.

So what I'm asking is, are the 5spd and Automatic MAIN harnesses the SAME? Or different?

The write up I was reading was talking about splicing the main harness(or so I thought) so that's what brought up this whole "I would rather just replace the harness" question.

Steve

MtnRacer

ttt

Steve

MtnRacer

Bump(again) I'll try PM after this...

Steve

Silkworm

Sorry, I was going to reply but I wanted to give you a better answer after reviewing the FSM wiring diagrams.. PM me and I'll check it later tonight when I get home.

MtnRacer

Great, thanks so much! =)

Steve

Silkworm

Ok, just took a look, specifically connector FE03, alongside the driver frame rail,, connecting the engine and front harness.

According to my 88 FSM.
On the Front harness, colors go:

B/R W/B *
B/W B R/W

On the Engine harness

* W/B B/R
R/W B B/W


On my car, the front harness goes:

B/R B/W? BR
BR B R/W

The engine harness:

Y/B * B/R
R/W B *

As you can see, on the engine harness, I have Y/B where there should be nothing, and where B/W and W/B (the two wires to the alternator) are, I have plugs.

And on the Front connector, I have BR and B/W where those two wires should go.

So I had to go hunting on my harness, it turns out that the B/W and W/B wires actually ran down to the Emission harness connectors in the passenger footwell. There, I believe, the emission harness would have the wires for the alternator.

Go figure, this is what I ran into on my car, it's spliced together from 7 or 8 different RX-7s of different years, and all of the harnesses were harvested off of different cars, all S4, and I'm pretty sure the main harness was off of an Auto (since someone here told me the harnesses were the same)

PaulC