Identifying a loose connection (1 Viewer)

[wyoclimber]

Hey guys,
I’ve been staring at the EWD and I can’t figure out where this connector should go. I’ve got a ‘94 FZJ80 with a crank but no start issue. I’m reasonably sure I’ve got it narrowed down to the fuel pump, but in the course of testing relays, I discovered a rogue connector. It’s probably the second set of wires off the wiring harness after it comes through the firewall into the engine on the drivers side.
Any help would be greatly appreciated.
Thanks!

 

[Malleus]

Try using these connection diagrams. Does the connector have a five digit number on the wire side? If not, it's not OEM.

If it has a five digit number embossed on the rear side, find it in the components diagram (it doesn't look like it would be a joining connector), and then go to that section of the EWD. The connector will be listed in that section, just to check that you have the correct ID.

 

[wyoclimber]

Thanks. I’m still not 100% sure what the connector is. I think I’m getting the EWD figured out, but for someone without much of a background in electrical, it’s a bit of an enigma. I’m now fairly sure that my issue isn’t in the fuel system after all. Realized I don’t have a CEL at key turn so my ECU isn’t getting power. I think I’ve got a bad ignition coil too. Kicking myself because I had recently changed my plugs an distributor so I had kind of mentally checked “spark” off the list.

 

[Malleus]

It's easy to determine if it's OEM or not. All the OEM connector housings must have the part number on them. If it's not, you're on your own to find out what it does. If it is OEM, it's in the EWD; you'll have to use the Wiring Harness Repair Manual to find the number (it's not in the EWD), but it' snot that hard.

If you need help finding the fault to the ECU, there are threads to help. If you can't find them or they don't help, ask. There are more than a few people here who can help.

 

[wyoclimber]

Thanks guys. I’m getting there on hunting stuff down.

 

[mudgudgeon]

Thanks. I’m still not 100% sure what the connector is. I think I’m getting the EWD figured out, but for someone without much of a background in electrical, it’s a bit of an enigma. I’m now fairly sure that my issue isn’t in the fuel system after all. Realized I don’t have a CEL at key turn so my ECU isn’t getting power. I think I’ve got a bad ignition coil too. Kicking myself because I had recently changed my plugs an distributor so I had kind of mentally checked “spark” off the list.

Check if you are getting a spark? Pull a plug and plug lead and rest against a grounded part of the engine, see if you get a spark when cranking

I recently had a bad connection at the distributor and no start, no spark, no CEL.

If you've recently had the distributor disconnected, you may have a bad connection

 

[mudgudgeon]

I discovered a rogue connector.

There's unused connectors all over the vehicle.

 

[ToyotaMatt]

Thanks guys. I’m getting there on hunting stuff down.

Check if you are getting a spark? Pull a plug and plug lead and rest against a grounded part of the engine, see if you get a spark when cranking

I recently had a bad connection at the distributor and no start, no spark, no CEL.

If you've recently had the distributor disconnected, you may have a bad connection

isn't that the dizzy plug ?

 

[mudgudgeon]

isn't that the dizzy plug ?

Not if it's back near the brake booster

 

[ToyotaMatt]

Hey guys,
I’ve been staring at the EWD and I can’t figure out where this connector should go. I’ve got a ‘94 FZJ80 with a crank but no start issue. I’m reasonably sure I’ve got it narrowed down to the fuel pump, but in the course of testing relays, I discovered a rogue connector. It’s probably the second set of wires off the wiring harness after it comes through the firewall into the engine on the drivers side.
Any help would be greatly appreciated.
Thanks!

View attachment 3277803

View attachment 3277804

@mudgudgeon sir ....

before you go on another TEq-SNIPE-hunt , chasing a possible long-stretchy and reach problem that never existed for anyone else ?



- i know that 1 link can blow and even 2 specific ones i am almost certain , results cranking / NO main engines IGNITION Dead in the water
you have not mentioned you confirmed and verify the all mighty steps 2-5 ?


- do u know to field test confirm and verify this is in solid working status order across the board ?

- if not , ask and ill help

if you know already , then hit your self upside the head with a wiffle ball bat for NOT posting you forgot to say in post 1 its good ,

- if u know already and forgot to know already steps 2-5 , till now .......

- i would RUN in fifth gear the hell out of hear now ...


- i personally would be army crawling to that fusible links multi meter in hand ,

 

[wyoclimber]

Much smacking upside my head has already occurred. Bad FL and bad ignition coil. I’m kicking myself pretty hard for not checking for spark first. I had kind of mentally checked it off because I just replaced a spark plug wires and distributor cap, without thinking about all the other potential failure points upstream. I had also visually inspected the fusible link, tugged on it, etc, but when I tested with a multimeter the other day, sure enough, one leg was bad.

 

[Malleus]

It's always the simple things...

 

[wyoclimber]

Well s***. Not my FL or Ignition Coil.

I think at this point I’m narrowed down to my ECM or my wiring harness.

Here is my saga, 1994 FZJ80.
New Plugs, wires, rotor and cap. Replaced these last year when I did my valve cover and spark plug well seals. They spark plug wells were leaking like crazy, probably 3 or 4 had a couple inches of oil in them. It ran fine for a few months after that and then went down.

The day it died, I was driving up a hill and it lost power pretty severely. Regained power towards the top of the hill, and then about a 1/2 mile down the road, on another hill, it died, and that was that. Cranks, but no start.
Seemed like a fuel problem, so I changed my fuel filter, as it was something I’d been meaning to do anyway. No change. Couldn’t hear my pump, so I pulled it out and tested it, it tested fine, strainer looks clean. Put it back in and jumped it with a motorcycle battery and it fires up fine.
EFI Main Relay - Good
EFI 15A Fuse - Good
FL - Good and replaced for good measure
Fuel Pump Relay - Good
Circuit Opening Relay - Good
Fuel Pump Resistor - Good
Ignition Coil - Good and replaced

CEL does not come on when key is turned, but turns on when port “W” is grounded.
12V at port W, 0V at E1 with key turned
Continuity at ground point EC - No voltage drop

I’m reasonably sure I have neither fuel, nor spark.

My wiring harness has foil/heat wrap by the EGR. Is that typical, or does that seem like a repair was done there? I’ll include a picture. Any advice would be greatly appreciated. I’m a one banana mechanic, and while I’ve learned a ton, I’m feeling pretty stumped.

 

[Malleus]

That's redneck engineering, for sure. It should have a heat wrap, but that aluminum foil isn't doing it.

 

[Malleus]

Two things: first, stop using the DLC1 to troubleshoot the problem; second, you need to use the ECU troubleshooting matrix (ppg 235-250) and the engine control EWD together to find and fix the problem. There are 10 steps to troubleshooting the ECU and none of them involve using the DLC. That thing was meant as a connection for the mechanic's handheld tester. It can be used for some simple diagnostics, but it leaves more questions than it provides answers. For example:

These are the DLC1 connections:

as you can see, the "W" and "E1" terminals supply power and ground to the MIL. (Follow the Y/W wire from the DTC to the lamp)

And that's exactly all it does. As long as the bulb works, shorting these two terminals will turn it on; all without using the starting logic that's necessary for troubleshooting.

 

[wyoclimber]

That's redneck engineering, for sure. It should have a heat wrap, but that aluminum foil isn't doing it.

Well, that’s good to know! When I looked closely, it definitely didn’t look stock, but I didn’t have anything to compare it to. Guess I’ll pull it apart and look at wiring. I’ve found a number of things on this rig that are dealing with a problem, but in kind of a half-assed way.

 

[wyoclimber]

Two things: first, stop using the DLC1 to troubleshoot the problem; second, you need to use the ECU troubleshooting matrix ppg 235-250) and the engine control EWD together to find and fix the problem. There are 10 steps to troubleshooting the ECU and none of them involve using the DLC. That thing was meant as a connection for the mechanic's handheld tester. It can be used for some simple diagnostics, but it leaves more questions than it provides answers. For example:

These are the DLC1 connections:
View attachment 3342052as you can see, the "W" and "E1" terminals supply power and ground to the MIL. (Follow the Y/W wire from the DTC to the lamp)
View attachment 3342056
And that's exactly all it does. As long as the bulb works, shorting these two terminals will turn it on; all without using the starting logic that's necessary for troubleshooting.

Gotcha. I will dive in further this evening. Playing with wiring and electrical is definitely out of my comfort zone as a mechanic, so I’ve got a lot to learn there.

 

[Malleus]

Not a problem. I know you've been given advice to use that terminal, by some who have previously used it successfully, but it's not helpful in this case.

LMK if you can't make sense of the EWD and FSM. I'll given you whatever help I can. FWIW, once you understand it, wiring is about as hard as plumbing.

 

[wyoclimber]

I haven’t had a chance to actually test anything yet, but I’m reasonably certain that my wiring harness got cooked. Once I pulled the heater hoses out of the way so that I could see a bit better, that foil job looks even worse and it’s definitely contacting the EGR. The clip that holds the harness off the EGR is missing as well. Considering that it looks like it’s been repaired there once before, I’m thinking replacement of the whole harness is my best option. My one question is, how likely do you guys think it is that a bad wiring harness could fry an ECM?

 

[wyoclimber]

Haven’t had a chance to work on the rig in a minute, but I just started digging in so that I can rebuild/replace my wiring harness. I was hoping to get some advice and opinions as I decide how big of a project this should become.
I’m probably at approximately 250k miles. I don’t know what previous maintenance has or hasn’t been done. I’ve put maybe 25k on it.
I’m thinking that while I’m replacing the wiring harness, I might as well pull the fuel rail and injectors, make sure everything is clean and flowing well.
I need to replace my radiator, as it’s starting to leak pretty badly along the tank seam. It’s not an emergency, but since I haven’t driven the rig for 8 months, I obviously don’t have to have it, so I’m thinking I should really try to get everything dealt with while it’s down.
The biggest question is, should I pull the motor and do my HG as preventive maintenance? Is it worth it if I haven’t had my HG go?
Anything else that should absolutely done as long as this thing is torn apart?
On a somewhat separate note, is it worth doing an EGR delete?