Electrical mystery: Headlamps, horn, hazard flashers.

[Jonathan Hanson]

On the way home from Overland Expo West yesterday we realized that the headlamps, horn, and hazard flashers on our '93 HZJ75 had stopped working. The three fuses that control those items are all fine, but there is no power to them. I can't figure out what would fail that would simultaneously cut off the feed to those two wires (one to the two headlamp fuses, another to the horn/hazard). The running lights work, so do the turn signals. Is there a relay in the circuit that could fail and cause this? Thanks for any direction.

Jonathan

 

[RhinoRig]

Check your fusible link. Power should always be on for those three items and comes from one of two links. You can check for power at the panel and if there is none, then it must be the link. No relays involved.

 

[Jonathan Hanson]

Check your fusible link. Power should always be on for those three items and comes from one of two links. You can check for power at the panel and if there is none, then it must be the link. No relays involved.

Thank you; I'll check that. I didn't know the 70-Series even had fusible links.

 

[prwillard2]

Thank you; I'll check that. I didn't know the 70-Series even had fusible links.

This is the partsouq diagram for my FZJ75. Put your VIN in and search "fusible" and it will show you the part and diagram.

https://partsouq.com/en/catalog/genuine/unit?c=Toyota&ssd=%24%2AKwE1ARAeX0pOb0lhRVBnN215WV5AMT4zMiA-DHwkdSI9JFshcnIvJTw1fXlzaGceK25kb2UiPTItITg5KCU8Izg1NjMhcnIlaSQ7Ij80MTpuZQQle392bmJBeHw5OCU8I0ZVR0xGfHxubnUjOiVAW0lpZXw3NDY5NzIjL3wzLyU8Izc_NzIwbnJgJWtiIj0kR1kUZ3lLUCxNVVNXIXJyKm5iIzozMHwAAAAAnX5Xpg%3D%3D%24&vid=0&cid=1&uid=366178&q=FZJ75-0027904

 

[OGBeno]

If it is the fusible link Jonathan, the part number will be 82627-60020 for replacement. Available anywhere Toyota parts are sold.

 

[RhinoRig]

The bigger question: why? What caused it to blow? Damn gremlins

 

[Jonathan Hanson]

Thank you for the links to the Partsouq diagram and the part number (and Onur, glad to finally meet face to face this weekend!).

Indeed, if it is the fusible link that will just shift the mystery.

 

[joekatana]

Did you check the headlights relay already ?

 

[Jonathan Hanson]

Well it doesn't appear to be a fusible link issue—I have power downstream from these three battery connections. I'll check for the headlamp relay, but wouldn't that be downstream from the fuse? And it still wouldn't explain the horn failing at the same time.

 

[Jonathan Hanson]

The worst possible thing then happened: Everything just started working again. Now I have zero clues as to the cause, and no guarantees the headlamps won't just blink off on a dark highway.

 

[jblueridge]

Are those connections at the battery as they were from the factory? It looks a bit like mine that I did myself (but I have like 5 wires there now).
I would dissect the one that feeds those ignition-independent devices: horn, lights and flashers.
I had my whole truck dead for a week until I realized that a non-factory battery lead was corroded and not making contact (invisibly inside insulation sheath).

 

[Jonathan Hanson]

Those are as they were when we bought the vehicle, except I've added some protection (heat-shrink, etc.). I'll check the one that feeds the headlamps etc., thanks.

 

[Tanner H]

Dusting off this thread to avoid a new one since i have the same issue.


1987 bj74 24v
Yesterday my dumb ass was moving one of my batteries out, and the daisy chain cable connecting the two batteries accidentally touched the intake manifold and sparked.

Now my headlights, horn and hazards do not work.

Runs and drives great. daytime lights and turn signals work.

-Fuses are good and replaced just in case
-headlamp relay clicks from what I can feel


I'm assuming fusible links but wondering two things:


-is there a way I can bypass my fusible link(s)for a few seconds just to confirm thats my issue?


-what would be a suitable readily avaialble fusible link that I could obtain pretty quick to trouble shoot? Or simply run an inline fuse with new wire? This is a high mileage rusty bj74 so not afraid to toss in something aftermarket or diy.

I believe 90982-08232 is the OEM number but honestly it looks like my current fusible link is aftermarket anyway (see photo)

​

​

 

[jblueridge]

The fusible links should be very close to the main positive battery terminal.
You can disconnect those wires and look closely at the links.
Sometimes they have a fiberglass sleeve so if they burn, damaged is contained.

I ended up buying US-available links at NAPA.
I had to mess around with wire terminals and such.

 

[Tanner H]

...well I think i found my problem here already...i should have looked harder. one of the wires was holding one by a single strand, and when i barely touched it it broke off.

also, is the black wire also supposed to be connected like this?

 

[jblueridge]

Here's a link to what I did.

fusible links

 

[Tanner H]

@jblueridge Thank you sir. so looks like i need to bundle the 3 wires back into a single ring and connect to the terminal. Will report back if this does not fix it.

 

[jblueridge]

They can each have their own ring terminal but eventually battery terminal gets crowded.

Are you sure those short wires are the fusibles?
Maybe someone removed them.
My new fusible links have writing on the insulation.

 

[Tanner H]

I believe that is the fusible link since it has 3 wires.
Yeah hard to say, I'm assuming someone hacked into those wires at some point but hard to say since the truck has had multiple owners. I bet those wires used to have writing on them but since they have been cut down so short its hard to tell.



That being said, the fusible wires from napa which is 5 minutes from my work. Will pop in there on my way home to grab some just in case.

I believe you used this one?

https://www.napaonline.com/en/p/BEL784695?srsltid=AfmBOoomC6Nn_c5Rpz1FoUcqsfinW9VWBnKPtv-y9eUYebRW9LTwaREX

 

[Felde]

EDIT We are talking a 74 here, right? That's different fusible links.. My bad.

Hi
Sounds like fusible link line 'A' blown.
The fusible links are connected to the battery at one end, and to the harness on the other end. By factory default, the connection to the harness is either a plug&socket connector (round) or eyelets on a bolted connector in a plastic box (depends on which link it is; I think Line A is the round plug&socket, but not sure. Go by wire colors).
You can check the fusible links by measuring voltage at the connector to the harness. No voltage there: Fusible link blown.
The factory fusable links are color-coded Y yellow (1.0,) L blue (2.0) or B black (1.25) and connect to the harness like this:
Yellow to white (Line A, your suspect),
Blue or Black to black (Line B, C, also feeding all other main lines trough the ignition switch).
(I only have the wiring diagrams for the heavy duty at hand; LJs might be different).

However, your fusable links do not appear to be factory.
Bypassing the blown fusible links ** for diagnosis only ** is possible; fairly easy on the one that connects to the harness by the bolted connector; not so easy with the pluged one. Measuring the voltage is easiest as that also is possible on the plug&socket.
Search the forum for fusible link. There is a member who fabricates replacements. There are also pictures in his post, showing the connectors.
Good Luck Ralf