DigDug

You said you got no voltage on ECU terminal 1A. Did you also test 1B? I ask because they are routed differently. If 1A didn't work, but 1B did, it might help to find the problem. Remember that 1B only gets battery voltage when the ignition key is turned to "ON".

I'd at least try to figure out if and where the harness is damaged before replacing it, but that's just me...

DigDug

Can't be good to have open holes in the manifold. You'll certainly want to put them back on.

DigDug

Check your battery negative post first. Make sure it's tight.

DigDug

Now go to the cabin fuse box. Remove the screws so you can get to the back of it. I've attached a diagram of the connectors on the backside of the fuse box. Locate connector JB-05 from the diagram, and disconnect it from the fuse box.

I've also attached a pinout diagram of the JB-05 connector. Test for battery voltage on the white/red (F) pin on the JB-05 connector. Once again, use a nearby bolt threaded directly into the chassis for ground.

If battery voltage is making it here, the problem is downstream (towards the ECU). Otherwise, the problem is upstream (towards the battery).

armanielite

Oh yes i forgot to mention this..there is no pin in 1B (it is empty). Yeah a bit odd i think, but there are no loose wires hanging or broken within the wire set for that connector. So it must have been empty from whenever i had the PFC installed.

DigDug

You're not putting the multimeter probe on the pins on the actual ECU box, are you? I meant to test the pins in the harness connector that connects to the ECU...

The reason I ask is because if you were, then the pinout diagram is reversed, and the empty pin would be where 1B is located in the diagram.

Test the pins on the harness connector, NOT on the ECU itself.

armanielite

I am testing the pins in the yellow connectors that plug into the ECU.

DigDug

Well, 1B should have a pin. The pin directly opposite 1B (opposite side of the connector) is an empty pin from the factory, so I think you're reversing the diagram. Look at the pin on the other side of the connector, and it should have a black/white wire going into it.

The pin locations in the diagram are as if you were looking at the receiving side of the connector (not the one you are testing pins on). It can be kinda confusing if you're not accustomed to it.

armanielite

ok will go check...no i think when i printed the diagram i rotated the pic to fit on my printer and i think i reversed it....am checking thw wires now....

armanielite

ok checked it again...1A 13volts...(1B 0 volts while igniton was turned on)


4A, 4B, 4C 18-22 ohms

DigDug

1A is blue/red and 1B is black/white, correct? If the colors match, you're definitely on the right pins.

If 1B doesn't have battery voltage with the ignition switch turned to "ON", then that's why the PFC doesn't come on. Other wiring issues aside, the thing would at least turn on if 1B got voltage.

If pins 4A, 4B, and 4C all show continuity to chassis ground, then the ECU is grounded properly, which is good.

armanielite

correct 1A is blue/red......1B white/black

DigDug

Good.

Okay, so forget the test I previously mentioned regarding the fuse box - that was if 1A wasn't getting voltage, but we're on a different circuit now.

Upstream, 1B goes directly to the EGI main relay, and then through the EGI fuse to the battery. You said you already checked all the fuses, so the EGI fuse should be okay.

I've attached a diagram showing the location of the EGI main relay (labeled "main relay"), which is the yellow one in the box behind the battery. Remove this relay. I've also attached a pinout diagram for the connector that the relay fits into. Test for battery voltage between the W/G pin (white/green wire, though you can't see it beneath the connector) and a nearby chassis ground.

If battery voltage is making it here, test the EGI relay itself. I've attached a segment of the FSM showing how to test it.

If the relay tests out okay, then the problem is in the front harness. Otherwise, it's the EGI relay.

armanielite

ok the EGI main relay is getting 12 volts through pin WG. Now when i tested the EGI relay from post A to post B im not getting a reading.....not sure im testing it correctly....im just using the volt meter and puting positive to post A and then just using a ground...then do the same for post B. Is this the right way to check it?

armanielite

ok wasnt sure if i was testing the EGI relay itself correctly so i took the cover off and looked at the brass fibers inside and the posts ...and all looks good doesnt look like anything has been arking.

DigDug

Use a spare wire to connect pin A to battery positive, and another spare wire to connect pin B to ground. When these wires are in place, you should get continuity between pins C and D. Then remove the spare wires, and you should no longer get continuity between C and D.

If the relay is working, then it's in the front harness.

DigDug

If the EGI relay is working, you should check the plastic wheelwell liner (front driver side). Look directly above the wheel. If there is a spot where the liner is worn through, check if there are any exposed wires above it. The front harness runs just above the liner, and lowered cars tend to get wear up in there. It will eventually wear through the liner and start eating into the harness.

armanielite

ok then i did test it right..i didnt get any continuity so i just replaced the relay.......ok i pluged everything back together put the new relay in and well still nothing....I for some reason decided to check the turbo timer and it doesnt work either so i tried to follow the wires to where it connects to and i believe it goes to the main relay box where the EGI relay i just replaced is...So I'm guesing its looking more like a bad harness coming out of the main relay box.....

any more tests for me to run?


i already checked to see if there was any wearing of the fender lining although my car isnt lowered..but there was not any wearing

armanielite

if it is the front harness..how much do they run?

DigDug

At this point, you know it's the front harness. There aren't any more connectors between the EGI relay and the ECU on 1B, so you can't really isolate it any further than you have.

Just so you know what you're dealing with, look at the attached diagrams. These show the front harness. It snakes around the perimeter of the engine bay and goes behind the dash. It's not an easy task to replace it.

armanielite

would the turbo timer be wired in this harness....the timer was already installed when i baught the car so im not sure where you would splice it in.......

also is it possable that instead of the entire front harness that its just the actuall relay box itself?

also any idea how much $$$$ were talking for the harness and possable installation

armanielite

anyone have an idea on price or have you done this job before on your FD?

FDNewbie

iTrader: (10)

Not necessarily. My motor (orignial, 88K) is making about 9psi in vacuum. I was real worried when I saw that...turns out both my friends' motors are making 8 - 9 psi in vacuum too. Solid steady vacuum, no leaks. It's also a sign of a tired motor

A new wiring harness is $800 from Ray Crowe @ Malloy Mazda (aka the cheapest you can find it).

armanielite

$800 yikes plus install which im sure is like $500 from the dealer...this royaly blows

um any possable that i might be the relay box itself? which might be a bit cheaper i would think

oh yeah about the vacuum when my car actually started vacuum was like 11 not 9 ( boost gauge off) but while trying to find the bad wire in the front wiring harness i found 2 block off plates missing so i would gather that those are kiling my vacuum readings..as soon as i get the front harness done or relay box done i'll be putting in the missing block off plates in

FDNewbie

iTrader: (10)

1) Find a low mileage harness from a wrecked FD, and use that. MUCH cheaper. 2) DO NOT let the dealership try and install it. You're crazy if you do lol. You'll come out w/ a blown motor and all other sorts of problems If they can't diagnose it, they just keep replacing until the codes go away You should talk to a WELL KNOWN rotary specialist in your area, and get a quote for fabricating a wiring harness for your car. Ppl have to do that anyways for some ECUs they run (Haltech I believe, for example). May be cheaper to just fabricate and install than buying a new one and installing it.