Relays/Gadgets - What is this one?

[watrob]

Back to that diode Waltrob mentioned. I looked at the 1981 FSM (August 1980) diagrams for various 40 series models:

-Bj40 (USA and Canada) shows the diode in the brake light warning system.
-BJ40, BJ43, & HJ47 series shows relay for Australia, otherwise neither diode nor relay indicated in association with the brake warning light system
-FJ40 & FJ43; bulb check relay for Australia again, and as above, neither system indicated for other areas
-FJ40 (USA & Canada) shows diode only

The only time the diode shows up is when the relay is absent. It seems like neither system is crucial to the operation of the vehicle given that it's absent for the world models of BJ40, BJ43, HJ47, FJ40, & FJ43. I imagine that the presence of the relay or the diode related to conforming to local regulations.

So it's one system or the other, but not together in the same harness as part of the brake light warning system. I've got the spare spot on for the relay on the 60 series relay pod I'm using, so I'll go with the relay for my situation I guess.

I wonder why the diode for some markets and the bulb check relay for Australia? What benefit/difference does one system have over the other? I won't be up at night pacing and thinking about it, but I sure would like to know.

I have both the bulb check relay and the diode, when I am back up at the beach house I might check it out. Are not diode's use for one od two things, one for over voltage to ground or two to stop volts coming back up the wrong way.

There is a lot transistors etc in these relays especially the fuel control relay and I wonder if this might be protection against volts coming back up the negative line?

 

[watrob]

And here is my EDIC relay. It is "squashed" into a really narrow gap between my glovebox and the LH door pillar:

View attachment 213492

And here is my "low/poor vacuum alarm" sounder. It is above - and slightly to the right of - my "blinker relay":

View attachment 213493


As I mentioned at the start - if anyone can help me identify that mystery relay/gadget - I'd really appreciate it.

Hey, thats what I have missing, "Low Vac Alarm" wondered what those wires went to. Did not think about an alarm as I have a brake light on the dash as well as the hand brake light.

 

[lostmarbles]

Back to that diode Waltrob mentioned. I looked at the 1981 FSM (August 1980) diagrams for various 40 series models:
-Bj40 (USA and Canada) shows the diode in the brake light warning system.
-BJ40, BJ43, & HJ47 series shows relay for Australia, otherwise neither diode nor relay indicated in association with the brake warning light system
-FJ40 & FJ43; bulb check relay for Australia again, and as above, neither system indicated for other areas
-FJ40 (USA & Canada) shows diode only
The only time the diode shows up is when the relay is absent. It seems like neither system is crucial to the operation of the vehicle given that it's absent for the world models of BJ40, BJ43, HJ47, FJ40, & FJ43. I imagine that the presence of the relay or the diode related to conforming to local regulations.
So it's one system or the other, but not together in the same harness as part of the brake light warning system. I've got the spare spot on for the relay on the 60 series relay pod I'm using, so I'll go with the relay for my situation I guess.
I wonder why the diode for some markets and the bulb check relay for Australia? What benefit/difference does one system have over the other? I won't be up at night pacing and thinking about it, but I sure would like to know.

Thanks HJ.

I've got my 1980 "Chassis & Body" manual in front of me now (at work) and every single wiring diagram there says "For USA and Canada". This is despite the fact that I bought this manual in Australia (from a Toyota dealer in Perth) around 1981!

When I get back home tomorrow I will search my computer for that Australian diagram but I'm doubtful I'll find it. (I bought a lot of old microfiche data off a USA-based MUD member but I think it all understandably applies to USA-market vehicles.)

Do you know whether that diagram is available aywhere on the Internet for downloading? (If you can see a "bulb check relay" there then getting hold of that diagram is the next step in solving the mystery for me.

And I may at last get my hands on a diagram that really does represent how my vehicle is wired!!!!!(Dunno what half these smilies are supposed to mean - but I've thrown in a few to show that this would make me ultra-happy!

Hey, thats what I have missing, "Low Vac Alarm" wondered what those wires went to. Did not think about an alarm as I have a brake light on the dash as well as the hand brake light.

Hey - I'm glad that photo was useful Robert.
Yes I have both the light and the alarm.

 

[Henry James the 47th]

You probably have the same manual that I have Lostmarbles - is it August 1980, publication # 36044E?

There is no separate diagramme for Australian trucks in this particular manual - those details are contained within the diagrammes. You will note that they use a dotted line to frame a subsection in the wiring diagramme, and then it is labeled in fine print "for Australia". You will note, for example, on the diagram for BJ40, BJ43, &HJ47 that there is a cordoned off section at the bottom of the picture illustrating the gauges in the instrument cluster, and that is 'for Australia'. If you look just to the right of that dotted cordoned off area, you will note that the brake warning components are illustrated for a second time, showing how the truck are wired for outside the Australian market.

Maybe you have a different manual though?

 

[astr]

Just a guess: Most vehicles have a provision that when you first turn on the ignition switch, all of the idiot lights light up to verify that they work. Could this be the purpose of this relay?

Easy way to tell is to unplug the relay and see what doesn't work any more.

 

[lostmarbles]

You probably have the same manual that I have Lostmarbles - is it August 1980, publication # 36044E?...........................................Maybe you have a different manual though?

Unfortunately it appears that my Manual is different HJ. It is publication 36044 without the E!

And without the E - there is no mention of any "bulb check relays" or other "Australia-specific" differences.

But that is not a problem now I've joined MUD. I've already received (by Email last night) the "1981 production vehicle wiring diagram" which has no reference to "USA and Canada" (unlike ALL the diagrams in my Manual). And it does show a "bulb check relay" and various other Australia-specific things.

Thanks Jon for sending me that!

Just a guess: Most vehicles have a provision that when you first turn on the ignition switch, all of the idiot lights light up to verify that they work. Could this be the purpose of this relay? Easy way to tell is to unplug the relay and see what doesn't work any more.

You're thinking exactly the same as me Astr.

I believe that when you turn the ignition key on (with an Australian model) the "Brake" light should light up (in one of the key positions) to prove that the bulb is not blown (and thus ensure more reliably that the safety-system will provide a warning of either "low brake fluid level" or "low/poor brake-boost-vacuum".

I'm not keen on trying to unplug the relay - (ever since I destroyed a "flasher relay" on a VW Kombi van by simply unplugging it when my wife and I were touring through Italy. - It broke in my hands with the printed-circuit-board split in two - Not easy to get a replacement part when you can't even speak the language!) Especially since I have no real fault that I'm trying to fix. (Just inquisitiveness to satisfy.)

But actually I think I do have faults associated with this "bulb check relay". And the really annoying thing is that I think they are "factory-installed faults".

In the 30 years (almost) that I have owned this vehicle, I have never seen the "brake fault light" light up. That's the LH light in this photo:


The RH hand is lit up because my handbrake is on and my ignition switch is in the "on" position (the position it normally sits with the engine running).

I know both bulbs are working because I swapped them before taking that photo.

I had also pumped the brake pedal so the "low vacuum alarm" was screaming at me as I took the photo. (God that noise is annoying - But not as bad as my son practicing drums!!!!)

Not only that, but I had removed the top of the brake fluid reservoir so the sensor should have been registering "low fluid level".



So why wasn't the left hand bulb lit up too.

Any body out there with an Australian-spec vehicle that has that left-hand light working? If so, in what key position is it activated? And which brake faults does it indicate? (I'm assuming from the wiring diagram that it should be both low-fluid-level and low/poor-vacuum.)

 

[Henry James the 47th]

Looking at the back of my manual, it lists in fine print the printing info (also to be seen in the opening pages of the manual itself). Printed: Sept 27th, 1988.

If you have an earlier manual, with the near-exactly same title, it could have been an earlier print. The first year of printing for the manual was Oct. 31st, 1980. I'm guessing that your manual, Lostmarbles, is an earlier printing and lacks some diagrams that mine contains.

Here's my take on function of the bulb check relay. If you track the wire running from the bulb check relay through to the ignition switch, usually a black-white stripe wire, you will note that it connects to the 'ST' terminal, or "START". This position is the most forward in rotation of the ignition barrel and follows a glow cycle, 'G' position on the ignition.

Now when you guys are talking about the relation between the relay to the warning lights turning on when you turn the key in the ignition, well, here's my take: The lights and gauges share a power feed wire, light blue-red stripe, which connects to the 20a. 'Heater' fuse. That fuse in turn is fed power from the ignition switch, when the key is in position 'M' (position 'IG' on an FJ40). This is the position before 'G' on the rotation. With the key in the 'M' ('IG') position, the fuel and temp gauges, oil pressure gauge all receive power and operate. The heater blower receives power too, along with the electric winch (if fitted), and sedimenter circuit.

Then, from 'M' postion, you turn the key to 'G' position, to put current to the glow plugs (on an FJ40, the key goes directly to 'ST' from 'IG'). To go to 'G' from 'M' may involve rotation the key backwards or forwards, depending upon the model and year of the truck. After a certain period has elapsed for the glow cycle, the key is turned to 'ST' to crank the starter. Power is routed to the starter and the bulb check relay simultaneously; the current runs into the relay, activating the switch in the relay. The switch pulled over inside the relay then allows connection between the red-white stripe wire (common to all the warning lights for the brake system) to the white-black stripe ground wire. Therefore the red-white is grounded. Where does the red-white go? To the "BRAKE" warning light itself. It follows that the warning light should come on when the relay is activated and grounds out the wire and completes the circuit. The bulb should come on for the duration of engine cranking with the starter. Once the starter gets the motor going, the key is relaxed back to the 'M' (again, IG in FJ40's) position. If the bulb does not come one while you are cranking the engine, and the relay is clicking when the key is in the 'ST' position, then either there is blown bulb, or a wiring defect. Likely the bulb in most cases. The bulb check relay does exactly what it states: it checks the function of the brake waning light when you are cranking the engine. It's a safety thing I guess. Without it, you would have no way of knowing if the brake light was working or not, since it would not come on during starting. If there was a fault in the brake system somewhere, and the bulb was burnt out, you would not know (that the fluid reservoir was empty, or the vac. reservoir had lost pressure...). I'm glad I want with the relay myself.

LostMarbles, it sounds like you have s fault in your brake light warning system somewhere, given the evidence you presented. I guess you'll be checking for continuity soon, eh?

 

[lostmarbles]

OK first I'll see if I can post an image of the section of wiring that I'm looking at now. (Fingers crossed that it won't turn out too small to be able to read easily.)



Damn. OK it is too small. But somewhere in there is the "bulb check relay".

(Next step will be to reply to you HJ - concerning all your helpful information in your last post.)

Have to do things one step at a time now . - Because my computer just developed a terminal haemorrage that made it crash and made me lose about 15 mins worth of verbal diaorrhea. (Never could spell that word - but who cares?) die--orrr- eeeee-ahhhhh

 

[lostmarbles]

Looking at the back of my manual, it lists in fine print the printing info (also to be seen in the opening pages of the manual itself). Printed: Sept 27th, 1988.
If you have an earlier manual, with the near-exactly same title, it could have been an earlier print. The first year of printing for the manual was Oct. 31st, 1980. I'm guessing that your manual, Lostmarbles, is an earlier printing and lacks some diagrams that mine contains.....

Yep. My manual is like me HJ- ------An original (August 1980 production)

.....Here's my take on function of the bulb check relay. If you track the wire running from the bulb check relay through to the ignition switch, usually a black-white stripe wire, you will note that it connects to the 'ST' terminal, or "START". This position is the most forward in rotation of the ignition barrel and follows a glow cycle, 'G' position on the ignition. .....

Yes. This is what I now see in the (New - for me) wiring diagram. My "bulb check" is supposed to be activated automatically when I turn my key right forward to the "start" position and crank my engine. (Yet my brake warning light NEVER comes on - Not even then.)

..Now when you guys are talking about the relation between the relay to the warning lights turning on when you turn the key in the ignition, well, here's my take: The lights and gauges share a power feed wire, light blue-red stripe, which connects to the 20a. 'Heater' fuse. That fuse in turn is fed power from the ignition switch, when the key is in position 'M' (position 'IG' on an FJ40). This is the position before 'G' on the rotation. With the key in the 'M' ('IG') position, the fuel and temp gauges, oil pressure gauge all receive power and operate. The heater blower receives power too, along with the electric winch (if fitted), and sedimenter circuit.
Then, from 'M' postion, you turn the key to 'G' position, to put current to the glow plugs (on an FJ40, the key goes directly to 'ST' from 'IG'). To go to 'G' from 'M' may involve rotation the key backwards or forwards, depending upon the model and year of the truck. After a certain period has elapsed for the glow cycle, the key is turned to 'ST' to crank the starter. Power is routed to the starter and the bulb check relay simultaneously; the current runs into the relay, activating the switch in the relay. ....

Yes I concur with everything up until this point.

...The switch pulled over inside the relay then allows connection between the red-white stripe wire (common to all the warning lights for the brake system) to the white-black stripe ground wire. Therefore the red-white is grounded. Where does the red-white go? To the "BRAKE" warning light itself.......

Here I only see ONE light being grounded and that is the "brake warning light" on my wagon (which I have never seen light up).
Perhaps other markets were given separate lights for "low-brake-fluid" and "low/poor-vacuum".

...It follows that the warning light should come on when the relay is activated and grounds out the wire and completes the circuit. The bulb should come on for the duration of engine cranking with the starter. Once the starter gets the motor going, the key is relaxed back to the 'M' (again, IG in FJ40's) position.

Yes. I can follow this.

...If the bulb does not come one while you are cranking the engine, and the relay is clicking when the key is in the 'ST' position, then either there is blown bulb, or a wiring defect. Likely the bulb in most cases. The bulb check relay does exactly what it states: it checks the function of the brake waning light when you are cranking the engine. It's a safety thing I guess. Without it, you would have no way of knowing if the brake light was working or not, since it would not come on during starting. If there was a fault in the brake system somewhere, and the bulb was burnt out, you would not know (that the fluid reservoir was empty, or the vac. reservoir had lost pressure...). I'm glad I want with the relay myself. ....

True except that the Aussi spec vehicles were given a noisy alarm too. Hey - That is something I haven't yet spotted on any wiring diagram (- But then I am struggling with a magnifying glass against an A4-size printout of the wiring diagram for "1981 production vehicles".)

LostMarbles, it sounds like you have s fault in your brake light warning system somewhere, given the evidence you presented. I guess you'll be checking for continuity soon, eh?

As usual - You've given me further things to look into HJ - Thanks. I'll check if the "low fluid level" activates my alarm.

I was going to say that I'd check if turning the key to the start position makes the relay click - but I'd have to disconnect the starter relay first. (Not sure if I want to do that right now.)

 

[Henry James the 47th]

Tom,

as I'm sure you're aware, most trucks in North America had "BRAKE" and "SEAT BELT" warning lights paired together. I located one with "BRAKE" and "FILTER" paired together, and that's what I am installing. You have "BRAKE" and "PARKING BRAKE" lights paired - exactly as is shown inside the dotted line-defined, "For Australia" area, and the bulb check relay is connected to the other brake circuit points, not the parking brake. I realized one solution does not quite fit all circumstances.

In my harness, I chose to wire it with the parking brake switch is connected into the rest of the brake warning system, similar to the set up shown to the upper right of the dotted line defined area in that drawing your posted. My truck was from Australia so it was wired like yours and had the same warning lamps combination originally. I'm using the other pattern of putting everything on the one light, and using a relay.

I'm glad you concurred with my conclusions about how the bulb check relay works. I was pleased to have figured it out, as electrical stuff is/has been tough for me to grasp.

You guys got a vacuum alarm buzzer, North American trucks had a seat belt alarm buzzer - which is worse?

 

[lostmarbles]

Hopefully there are Aussie and Kiwi BJ4#-owners reading this who can now tell me whether their left-hand "brake warning light" ever lights up (and if so - exactly what causes it to do so).

I've gained a lot from this thread.

It looks like the "brake warning light" should light up whenever I turn my ignition key to the start position as an automatic "bulb check". But I can't remember whether I have EVER seen it do so (certainly in the last decade).

In other words, I just want to make sure that the light actually works (as we now believe it was intended to) on other people's vehicles before I put "repairing mine" on my list of "jobs to do".

I've checked the fluid level and it doesn't activate the alarm. In fact shorting the terminals together (with the key in the on/run position) does nothing at all.

 

[jasonmt]

I'm not keen on trying to unplug the relay - (ever since I destroyed a "flasher relay" on a VW Kombi van by simply unplugging it when my wife and I were touring through Italy. - It broke in my hands with the printed-circuit-board split in two - Not easy to get a replacement part when you can't even speak the language!) Especially since I have no real fault that I'm trying to fix. (Just inquisitiveness to satisfy.)

I would not worry about busting the relay (Toyota Relay M4, 12V 22A, 90987-02004), it is such a common part that I have at least 20 of them kicking around the shop as they are used quite liberally across the Toyota lines.

 

[lostmarbles]

I would not worry about busting the relay (Toyota Relay M4, 12V 22A, 90987-02004), it is such a common part that I have at least 20 of them kicking around the shop as they are used quite liberally across the Toyota lines.

Thanks for that Jason - Very handy to know.



Update 14 March - This thread has obviously "stalled" without me getting all the info I want - so I've decided to start a new thread called ----What does your "bulb check relay" do? (Aussi spec BJ)