Where does the wiring harness typically get rubbed raw?

[notathomie]

I am battling a hot shut off problem. I am now getting PO172.

The FSM has five items to check:

1. Fuel line pressure
2. Injector blocked
3. O2 sensor
4. MAF
5. Engine coolant temp sensor

I replaced the O2 sensor, MAF and engine coolant temp sensor.

But to no avail.

Today I will take a look at the fuel pump. (Both the pump and assembly are new)

I am also examining all the typical problem spots where wiring harnesses get rubbed raw.

What trouble spots am I missing?

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TYPICAL HARNESS TROUBLE SPOTS
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1. Main engine wiring harness where it passes by the EGR valve

2. Main engine wiring harness where it passes above the glove box frame and heads into the ECM

3. Fuse box under the hood: I noticed a spot where two cable runs (with connectors) loop above the bottom of the fuse box and over the fuse box frame. These cables and their connectors almost pass into the front driver wheel well. I had no damage here, but it seems like a good place to check

4. Fuse box under the hood: the wires leading to and from the EFI relay are under sized on 3FEs. They get toasted. (I have an FZJ80 and my EFI relay gets roasting hot. But have not had a chance to switch in a cold EFI relay during a shut down to see if this is part of the problem)

5. Above bell housing. Wires from the main engine wiring harness go to the O2 sensors and transmission. I believe I read somewhere wires get rubbed raw here.

6. Fuel pump assembly: two wires that go down to the pump rub against the brackets that support the pump.

I have seen references to a problem spot where the wiring assembly goes past the firewall. The firewall is the back of the engine compartment, correct? Since the wiring harness is protected by a rubber "washer" / bushing, I do not see how it can get rubbed raw here.

Is this the correct spot to trouble shoot on the firewall?

I noticed one area behind the glove box where the wiring harness loops up and over a part of the dash frame.
This spot is to the right of the black box behind the dash that says Denso 445800-7100.
This looks like a potential trouble spot. But I had no problems here.

What am I missing?

 

[Proven]

I've seen a lot of posts regarding #1 on your list. There is a lot of heat there. In that location it isn't rubbing raw, but melting of plastic wire coatings and tape that lead to issues.

Then checking the fusable link is pretty high on the diagnostic trouble tree.

 

[notathomie]

Good point on the fusible links.

This should the first place anyone looks. Particularly if the CEL light does not come on.

Also, the inspection of the fusible link wire should be thorough. One must move the loose sleeve over the wires to inspect the area of the wire under the sleeve. I had a failure there and missed it the first time I looked.

In terms of the engine wiring harness under the throttle body, it definitely can rub raw. I had a slightly damaged wire there.