Isuzu County wire loom - fire

[Land Tiger]

I had a fire in engine bay last week. I think the main power feed wire has been rubbing up on the metal casing of the air filter. The engine loom is 37 years old, so it has started to deteriorate.
The loom is a mess from the start solenoid across the firewall to what I think is the oil/reverse relay and some of the stop circuit. I can't see any damage behind the fuse panel inside the truck but will pull out more of the dash next week.
I have the circuit diagrams in the manual (though the diagram around the reverse/oil relay is a bit different)
I am thinking of doing this myself.
What size wiring should I be using? The main sensor wires (eg. stop, oil pressure, reverse) I was going to use 18 AWG
which is rated for 14 Amps. The main Brown wire power feed wire from back of starter solenoid I am thinking of 10 or 8AWG - wire rated at 22 Amps.
I will try and get some different colours but will spend time to label the wire at connectors with heat shrink.
Any suggestions for wire gauge would be appreciated.
What a mess to start in the new year!
David

[p38arover]

Have you seen this: Circuit Breaker Kit 40A, Perentie - KLR Automotive (https://klrautomotive.com.au/circuit-breaker-kit-40a-perentie/)


A glaring fault in the Perentie (and early 110 as well) wiring harness is the unfused battery power that passes into the dash (on multiple wires). With age these wires can chafe and short out, usually melting the main wiring harness in the process (and some parts of the dash as well).

[Land Tiger]

Hopefully doesn't happen to anyone else and this thread prewarns.
I had put a fusible link on the alternator output, a cut out switch on the winch and multiple fuses on any new circuits.
But....as pointed out, this live feed wire is not fused. :bat:

[Land Tiger]

I have no electrical experience short of installing a couple uhf radios, so this is a huge project. I either repair or write this vehicle off...and I can tell you I love my Landie and have owned this for many years.
I have spent the last week slowly labelling what I can, taking lots of photos to help remember what colours go where. I have a Dyno label machine to label. I have the Australian supplement handbook with circuit diagram.
I have removed both wheel eyebrows on front guards and removed the harness from starter motor to alt. and across firewall to back up relay.
The starter wiring was very difficult to remove as the retaining nut was too close to chassis. I had to remove to three retainers and wiggle it to give room.
The main harness goes to the head lights and indicators.
Removed steering wheel and dash panel.
The speedometer only showed current speed, the trip meter didn't work and the lights didn't work. No wonder on looking, the bulbs have melted into the back...Will make sure the bulbs next time are correct wattage.
The harness is now free across the dash but is still jammed at back of dash where the harness enters the firewall.
My problem is that I have under dash a/c unit that looks like I will need to remove to finally remove the harness to get it onto the bench.

[Land Tiger]

I need some help from the Forum.
I have a Backup Relay with 6 pins that was up near the brake booster.
I can't find a part number to replace it.
It is JEDICO with some numbers 5 82550......
Part of it has melted where the main power wire went (Brown).
Thank you

[p38arover]

Not this one? It's an alternative engine stop relay for the Isuzu.

182920

The other stop relay is this one:

182921

Although they are only 5 pin.

[Land Tiger]

Hi Ron,
It definitely is 6 pin, it is a relay to ensure that reverse lights can only be activated when oil pressure has activated relay eg on only when engine running.
It has Grey wire goes to oil switch, green going to reverse circuit, Black, two Browns and brown/white which is the dash oil light. Not the isuzu stop relay.
It is the "back up Relay" in electrical circuit diagram, 3.9 diesel models. Unfortunately, can't find any part numbers.
Cheers,
David

[p38arover]

Yes, the reason for that is to stop the reverse lights flattening the battery if the vehicle is left in reverse with the ignition off.

I'll be going to KLR sometime next week so I can ask Brad.

[Land Tiger]

Hi Ron,
I think I am over thinking this. So long as I have a 6 pin relay, know what the coil activation pins are and NO and NC pin sets are a 30 - 40 Amp Relay should be ok.
So I will keep plugging on slowly.
Thanks
David

[Land Tiger]

I have removed the engine harness. The alternator was very easy, just pull the round connector and remove the earth wire. The starter was a challenge. The main feed wires had the terminal bolt so close to the chassis that I had to remove the three retainers and move the starter forward. On the Isuzu's exhaust there is also a bracket that connects to the starter bolt. It had to be removed. I will need the space to put the connectors back on when harness rebuilt.
I spoke to my local AE who said that there may have been a few faults along the loom as it normally burns from the short down to the main feed. I think that the main feed wire goes up to the reverse/oil switch relay then loops back down the harness into the main (dash) harness.
Some of the wires going through the firewall have been burnt so I had no choice but to remove and inspect this harness as well.
My Landrover 120 has an a/c under the dash which I sourced from a td5, the condenser from a holden astra, I can't remember the compressor, and a county double fan system. It works well......however, to remove the wire harness involves moving the dash and bringing the A/C dash unit forward enough to remove all the retaining screws.
I used my camera and took multiple pictures of where wires and connectors go. Used a dymo label machine with plastic labels on all wires as they were being disconnected.
It is a slow process.
Pictures to follow...

[Land Tiger]

This relay was up on firewall near brake booster. I am unable to source this relay so think I will rewire it with standard LR 5 pin relays. This will give me standard sizes throughout the electrics.
I have a length of brown 6mm wire to replace the main feed wire. Other wires I will replace with 4 mm wire. Colours will be what ever and I will keep a modified wire diagram.
Any suggestions will be helpful, especially on alternative wiring of relay.
I will not be using the plastic electrical tape...that is just a sticky mess at best.

(Oil Relay 6pin diagram from Red90 on Forum, Thank you for the diagram - hopefully this can be changed to this 5pin diagram )

[p38arover]

I couldn’t ask Brad. He’s away. I might try James as I’ll be there all this week to help out as they down 4 people because they are on holidays.

[nevik51]

Land Tiger the better option is to have 4x 20a fuses as i believe there is 4 or maybe 5 (i am to lazy to lift my bonnet to count feed wires to the interior fuse panel) cables that have to be protected.By having 4or 5 fuses protecting each cable so if just one cable shorts out there will be still power feeding the other circuits & then it would be easier to trace the electrical short on the circuit that did trip that fuse.

[Land Tiger]

Hi Nevik51,
There are a few circuits that are not fuse protected, eg. Reverse lights, wipers.
The main issue is that what KLR sell a kit for and that is the main feed wire.
I will be sorting out the fuse box and much of the add- ons from me (radios, chargers, A/C circuits) as I make the harnesses tidier. All the separate fuses I have will go through the main fuse panel.
Rewiring a harness is not a job I ever want to do again.
This has been a big learning curve for me, and not knowing what that 6 pin relay on firewall did initially and not being able to find a part number has made it difficult.
David

[Land Tiger]

Help needed.
In previous photo of burnt harness, I am trying to find a green wire that will go to reverse switch. Does a green wire exit near the relay alongside a yellow and black earth wire?
Thanks,
David

[Land Tiger]

I have been looking at all the harnesses to find a possible position for the green wire from the relay to activate the reverse circuit. I had no response when I asked for a photo on this forum. I understand why.
If you look in the Australian electrical circuit diagrams for the 3.9 Isuzu supplement I was tracing a green wire that did not pass the fuse panel.<br>Well, I think my Landrover diagram is different to what I have on the garage floor. It does have the engine stop assembly but also comes with Ignition light resistor, it also has extra wires behind fuse panel which look original.<br>It looks like a 4 cylinder diesel diagram modified.<br>So<u> <strong>I think the green wire was in the harness but not used</strong></u> (I could see remnants of green plastic). The reverse circuit is powered from the fuse box.<br>So, lesson learnt, Probably most of the Isuzu Landrovers will have different circuits.<br>If that is right then I will need to rethink my relay diagram.
<br>Will continue mapping out wires.