Wiring issues help (1 Viewer)

[BJRowles]

Hi all, as the title suggests, I'm after a wiring diagram for Australian delivered FZJ80R's.

Specs on my 80 are as follows;
1993
1FZFE
GXL
Manual
Right Hand Drive
Australian Delivered (99% sure of this)
Pre catalytic converter oxygen 02 sensor
No EGR

I am currently diagnosing an issue with intermittent stuttering and running on a couple of cylinders after heavy rain and wind combo. I've owned the vehicle for 4 years and haven't experienced these issues until this year with the wild weather on the south east coast of Australia. Happened once in January and once again now in late March. The fault seems to go away on its own after a few days but not after the engine is at operating temperature and driving.
Fault is still present at time of post.
When I managed to limp the car home I had cleaned out all EFI and ignition system connectors with contact cleaner, allowed them to dry out completely before reassembling.

None of them had water ingress or any signs of corrosion or damage.
MAF has been cleaned, Distributor has been cleaned.
Airbox and filter also dry with no signs of water ingress.
Accordion air pipe also dry with no signs of water ingress or cracks or leaks.

I have been in the process of replacing items as preventative maintenance. All the following parts are OEM Toyota parts.

Distributor cap, Distributor button, HT leads, Coil, Spark plugs (Bosch Platinum Iridium + checked gaps)
Fuel pressure regulator, In tank fuel pump, Fuel pump relay
Knock sensors x2
Coolant temp sensor for ECU

I also have a set of genuine injectors and genuine fuel filter ready to go in when I have the time.

After checking codes, I found I have Diagnostic Trouble Code (DTC) 42 which from research is a problem with the Throttle Position Sensor (TPS).

The reason I am chasing a wiring diagram so specific is because the wiring diagram I've been using doesn't seem to be correct as I have found a discrepancy between what the 1994 wiring diagram says and what is on my plug for the ECU. Please refer to the photos attached for what I'm talking about.

So, the middle ECU plug, from right to left starts at pin number 09 and finishes on 16.
Pin 10 (VTA) is a green wire with a black trace (correct as per the photo and wiring diagram)
Pin 11 (IDL) is a green wire with a red trace (incorrect as per the photo and wiring diagram)
Pin 12 is a green wire with a white trace as per the photo.

As you can clearly see, pin 11 is green with a red trace (VC) on the ECU but as per the wiring diagram this is incorrect.

After doing continuity tests, I have confirmed the pins on the TPS are in fact correct and correspond with their colours, however their wiring to the ECU has completely thrown me off.

Thoughts on this? Surely it's something I've missed right?

 

[NeverFinis]

If it rings out..it rings out.

I don't know why it is G-R and not G-W on pin 11, connector E 9. Perhaps there is an early or late 1993 EWD, or an addendum. What is the build month/year?

 

[BJRowles]

I mean true, but would be nice to have the correct diagram too.

04/1993 according to the plate in the engine bay.

 

[BJRowles]

If it rings out..it rings out.

I don't know why it is G-R and not G-W on pin 11, connector E 9. Perhaps there is an early or late 1993 EWD, or an addendum. What is the build month/year?

View attachment 3876031

I mean true, but would be nice to have the correct diagram too.

04/1993 according to the plate in the engine bay.

 

[NeverFinis]

How many connectors does your ECU have? 3 or 4?

G-R on pin 11 matches an early 1FZ-FE ECU. It is for VC though.

BTW, my leading suspect for your intermittent issue is probably a worn wire in the engine harness. Moisture is shorting it to another wire, or GND, inside the harness.

 

[NeverFinis]

Another question, is it random which cylinders the engine is firing on or is it only a specific ones that are still firing.

Also, check your injector connectors for damage, and moisture. Unplug them, and inspect each one.

 

[BJRowles]

How many connectors does your ECU have? 3 or 4?

G-R on pin 11 matches an early 1FZ-FE ECU. It is for VC though.

BTW, my leading suspect for your intermittent issue is probably a worn wire in the engine harness. Moisture is shorting it to another wire, or GND, inside the harness.

Its a 3 pin connector, please refer the photo attached.

You're more than likely correct about the worn out wiring, hence the need for the correct wiring diagram so I can check voltage drop, continuity and shorts.

Is there a common place on these engines and wiring harnesses for moisture ingress and wearing out? I've read that EGR spec'd ones have an issue with wiring. Any idea where the Achilles heel is for the AUS ones?

 

[BJRowles]

Another question, is it random which cylinders the engine is firing on or is it only a specific ones that are still firing.

Also, check your injector connectors for damage, and moisture. Unplug them, and inspect each one.

Seems completely random, although this is something I have not checked yet when this issue occurs.

Thankyou for the advice, I'll be having a look shortly at the injectors.

 

[NeverFinis]

The reason I am asking about the firing is that the injector harness has a couple of splice points, and it could help locate a specific area of the harness to look at if you knew if the firing was random, or not. Pull spark plug boots one at a time to check rpm drop.

The 1993 EWD I was looking at shows a 4 connector 1FZ-FE ECU as well as the 1994 EWD you are looking at.

Need to find a EWD with 1992/1993 1FZ-FE with 3 connectors. I am guessing that 1FZ-FE with manual transmissions will have 3 connectors, not 4.

In the resource section here, there is a 1992 70 series with the 1FZ-FE with 3 connectors.

 

[NeverFinis]

probably easier to disconnect the spark plug wires at the distributor on a 1FZ-FE.

 

[BJRowles]

The reason I am asking about the firing is that the injector harness has a couple of splice points, and it could help locate a specific area of the harness to look at if you knew if the firing was random, or not. Pull spark plug boots one at a time to check rpm drop.

The 1993 EWD I was looking at shows a 4 connector 1FZ-FE ECU as well as the 1994 EWD you are looking at.

Need to find a EWD with 1992/1993 1FZ-FE with 3 connectors. I am guessing that 1FZ-FE with manual transmissions will have 3 connectors, not 4.

In the resource section here, there is a 1992 70 series with the 1FZ-FE with 3 connectors.
View attachment 3876137

Exactly the reason why I wanted to find the right wiring diagram, I know these harnesses splice and piggyback off different things.

Absolute legend for finding that, I'll have a gander and see what I come up with.

 

[BJRowles]

probably easier to disconnect the spark plug wires at the distributor on a 1FZ-FE.

Very good point, I was just thinking to myself how I'm going to check that with all the intake still on

 

[BJRowles]

I think I found a winner here, both of the 1992 PDFs under the 80 series tab seem right so far.

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!

www.cruisercult.com

 

[BJRowles]

Update on previous post, those service manuals still aren't matching what I have in my car

Going to try to replicate the issue and isolate which cylinders are missing

The reason I am asking about the firing is that the injector harness has a couple of splice points, and it could help locate a specific area of the harness to look at if you knew if the firing was random, or not. Pull spark plug boots one at a time to check rpm drop.

The 1993 EWD I was looking at shows a 4 connector 1FZ-FE ECU as well as the 1994 EWD you are looking at.

Need to find a EWD with 1992/1993 1FZ-FE with 3 connectors. I am guessing that 1FZ-FE with manual transmissions will have 3 connectors, not 4.

In the resource section here, there is a 1992 70 series with the 1FZ-FE with 3 connectors.
View attachment 3876137

Update on the link i posted earlier, those service manuals still aren't matching what I have in my car.
The 70 series diagram seems to be the closest so far.

I'm going to try to replicate the issue and isolate which cylinders are missing by pulling the HT leads as you suggested.

Following that, inspect and repair the wiring harness and replace injectors while its apart.

 

[NeverFinis]

You could also listen to each injector to see if they are firing.

Long handle screwdriver with the tip placed against each injector and listen at the handle. You should hear a ticking.

 

[petegangies]

FYI, your model doesn't have a cat converter at all. I know my 1994 Aus FZJ80 doesn't and didn't from factory. The single factory o2 sensor, sits behind a muffler on the down pipe.

 

[BJRowles]

Update: Repaired wiring harness and replaced the VAF and 02 sensor. Still have the same fault only I have no error codes this time.

I read on another thread that I could have a fault not electrical but mechanical and not throwing a light. Stumped where to start as I've replaced nearly everything related to the EFI system. At a complete loss

 

[NeverFinis]

Have you checked your grounds, especially your engine grounds? The one on the back of the head to the firewall can be mounted incorrectly and/or poorly grounded.

I don't recall if you identified if it is the same cylinders misfiring or is it random.

I would isolate it to either spark, or injector. Identify which cylinders are misfiring, and then check to see if injectors or plugs...

 

[Azca]

I know you are chasing this as a wiring issue. You indicated it only happened after a hard rain, which I am assuming you are getting quite a bit of water under the hood. If your spark plug wires and caps are not properly seated, water can enter from on top of the valve covers and get into the spark plug cavities. This can cause the misfire you are describing. Perhaps remove the wires, blow out the holes and let dry with a fan blowing across the top of the engine.