(Another) HDJ81 starting/electrical issue (1 Viewer)

[EvgMZ1HDT]

Hi all, posting as a new thread even though I'm having many of the same issues on similarly titled threads, because the fixes on those threads haven't worked (at least not yet) for me.

I was driving my HDJ81 and noticed-while still driving-that all the gauges except the fuel gauge and speedometer stopped working. Radio was still working, truck's clock as well, blinkers etc all were still working. The windows did not work. When I turned the truck off and tried to turn it back on, nothing. No clicking, nothing. Here's what I know:
- both batteries are fine, showing 12+ volts, and all electrical I mentioned above still work (radio, headlights, etc). Turning the key turns on all accessories, but gauges don't turn on, I just get the warning light above the voltage gauge.
- I checked all fuses in the main relay box and power outlet box, and all connections I could check, all seem fine.
- Measured voltage to the starter, it was at ~12v (though didn't check when trying to turn the car on (been doing this solo so far)
- I managed to run 12v from the starter battery to the starter relay, and got the starter to click/engage, but nothing beyond that

This is as far as I've gotten, beyond reading all related threads I can find on IH8MUD and the engine/chassis manuals, but don't feel like I know how to do much beyond this, such as check for continuity at the starter relay, VCT or VTR or NSS (I don't even know where the latter 2 are or what they look like!). Given this happened while driving, and the truck drove fine after it happened, and the only thing NOT working is the ignition, I'm inclined to think its the ignition switch. But I don't feel like I know how to check this, and of course don't want to go throwing money at something without knowing the problem.

Any help would be greatly appreciated, especially since I can't find a single shop anywhere near me that's willing to even take a look...

 

[Squash]

Make sure your batteries are fully charged, should show over 12 volts.
Make certain the battery post connections are clean and tight.
You can crawl under the unit and jumper the main power at starter to solenoid lead, this will crank the starter if your batteries have enough juice.

 

[AirheadNut]

My first suspect would be fusible links. Having some stuff still working while other stuff is dead seems to indicate to me that one of the links has burned out, killing power to a section of the vehicles electrical system.

 

[Dusten]

I suspect you have an issue in the ignition switch.
You have power to some elements that the switch feeds, but not all. The fusible links and main 50 amp fuse feed the ignition circuit. So if they've failed you'll lose everything.

Here is the wiring for the fusible links and ignition.

Start on the right with what does work and doesn't and chase it to where they split.

Fusible links are easily tested with a multimeter.

 

[Dusten]

My first suspect would be fusible links. Having some stuff still working while other stuff is dead seems to indicate to me that one of the links has burned out, killing power to a section of the vehicles electrical system.

Yes and no.

There are two fusible links.

But he has some stuff working and some not. All fed by the same link.

 

[EvgMZ1HDT]

Thanks for the feedback. I checked the battery terminals and other connections and they were all good. Tried to jump the starter via the starter switch but it didn't work (I suspect because it was only getting 12v).

I did find that some of the connections on the fusible link right off the starter battery were corroded, those were only on the glow relay wires and connections. And when I cleaned them I was still getting 12v on the downstream end of the wires, so think that FL was ok.

I'm inclined to also think its the ignition switch, so will try to test it out when it warms up. Anyone have a good picture of it and how to access what I need to test? Haven't felt 100% confident I've got that figured out yet.

 

[Squash]

The fusible link may light up your test light, but will it handle a load? If in doubt either replace the fusible link and/or bypass the wire up to the starter relay with a fused line from the battery until you get a new fusible link.
PS
If done properly you can start with only 12 volts.

 

[Dusten]

The fusible link may light up your test light, but will it handle a load? If in doubt either replace the fusible link and/or bypass the wire up to the starter relay with a fused line from the battery until you get a new fusible link.
PS
If done properly you can start with only 12 volts.

If the fusible link was bad leading to the ignition why would he have half the circuits off the ignition running?

If the fusible link fails the truck will die because the fuel plunger will close.

 

[Squash]

Crawl underneath with two screwdrivers or a jumper wire and quickly tap the main power feed to starter at the starter(has a rubber boot) and the solenoid feed just above.
Be careful you don't touch anything else but those two points.
By doing the above you will engage the starter. Now if you are comfy turn on the ignition and the truck will fire up.
I choose to start from the starter when my unit gave me trouble. Ended up being the fusible link even though at test light showed OK.
While into the system I also tapped in a fuse power source from the drivers battery to solenoid feed. This allows me to start with only 12volts.
I consider this my emergency system and works great for bumping the engine when changing a tight belt or if you ever have a pooched battery.
Use a momentary switch, mine is at the Passenger battery.
PS I also wasted time at the NSS, Ignition and various other crap.
The beauty of this is that you can still drive whilst you figure things out at your own pace.

 

[nickolai]

The wiring diagram posted earlier in this thread only tells part of the story - here's the full diagram for a 12-24v start HDJ81 (I have the FULL EWD if people want it).
There is another Fusible link on the LHD battery, on my truck it's green, highlighted yellow below.

It provides 12v to the starter relay at all times, check that its good and that you can see 12v on the white wire/pin on the plug at the starter relay.

This may not explain your half accessories issue but might explain your no-start.

 

[Dusten]

The wiring diagram posted earlier in this thread only tells part of the story - here's the full diagram for a 12-24v start HDJ81 (I have the FULL EWD if people want it).
There is another Fusible link on the LHD battery, on my truck it's green, highlighted yellow below.

It provides 12v to the starter relay at all times, check that its good and that you can see 12v on the white wire/pin on the plug at the starter relay.

This may not explain your half accessories issue but might explain your no-start.

View attachment 3258946

If you look at what I posted his not starting is also lined there. The ignition circuit. I had literally the exact same issue.

Ithe ignition fuse and charging fuse are on that half of the ignition.
This explains why it won't start. It explains why the alt light is on. There are tons of threads about lose connections and failed switches causing this.

But again, a simple resistance check, not a test light, of the fusible link will tell the story.

 

[nickolai]

If you look at what I posted his not starting is also lined there. The ignition circuit. I had literally the exact same issue.

Ithe ignition fuse and charging fuse are on that half of the ignition.
This explains why it won't start. It explains why the alt light is on. There are tons of threads about lose connections and failed switches causing this.

But again, a simple resistance check, not a test light, of the fusible link will tell the story.

FL ST is not on that diagram.

 

[Dusten]

FL ST is not on that diagram.

I didn't say it was.

I also think that because he's having more than a no start issue he needs to look at issues that go beyond the fact it won't start.

On the ignition circuit side the FL is before the switch. So if FL AM or the AM fuse were am issue he wouldn't have headlights or blinkers. Because the ignition circuit wouldn't have power.

He's getting power to the ignition but not past it on all legs.

There are two legs of the ignition circuit.

From his description 1 has power and 1 does not.

This is the same symptoms I had.

But again, if you guys think it's a fusible link a simple resistance check with a multimeter will tell you real quick if they're good.

 

[Dusten]

All of his issues are on am2 of the ignition circuit.

 

[EvgMZ1HDT]

All of his issues are on am2 of the ignition circuit.

Definitely with you that the issue is downstream of the AM1 fuse since I have wipers, turn signals etc. But I was thinking the issue was at ST1 since I have ACC and IG1 working. But I definitely don't know enough to say for sure, just know that the 7.5a IGN fuse downstream of IG2 is fine. Either way seems like its something within the Ignition Switch, which I tried to find and test yesterday but without any luck.

I couldn't find anything that looked like the diagram in the FSM; Dusten do you have a picture of it I can use as reference, by chance?

 

[Dusten]

Definitely with you that the issue is downstream of the AM1 fuse since I have wipers, turn signals etc. But I was thinking the issue was at ST1 since I have ACC and IG1 working. But I definitely don't know enough to say for sure, just know that the 7.5a IGN fuse downstream of IG2 is fine. Either way seems like its something within the Ignition Switch, which I tried to find and test yesterday but without any luck.

I couldn't find anything that looked like the diagram in the FSM; Dusten do you have a picture of it I can use as reference, by chance?

Here is testing it.

And how to pull it

Ignition switch replacement procedure.

I've searched, I've searched, I've searched...... Seriously though I've read through a few dozen threads and can't seem to find some info on how the ignition switch comes out and is replaced. No, I haven't started digging into it yet as I prefer to search and do as much research as possible...

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