No Glow plugs

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Eric Winkworth

Eric Winkworth

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Feb 28, 2005
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I'm trying to track down the problem I'm having with my glow plugs...

My relay clicks, and then I get no power at the resistor, or bussbar or glowplugs, the wires look like they are in mint shape.

Do I buy a new resistor? How do I check it to see it is is good?

Keep in mind, I turned the glow plugs on an off a bunch of times when my batteries were drained, trying to get the motor to turn over, which I realize now wasn't a good idea and I blew something....
 
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Is there power coming out of the relay to the next point in the system when the glow light is on?
If not check for continuity across the relay on the side that supplies the glow plugs. Be CAREFUL when doing this and have the relay isolated (nothing connected to the glow plug side) or you could blow your meter! You WILL need to have the side from the ignition switch connected though.
That's big (glow plug) wires off the relay, small (control) wires on on the relay.
You check continuity on the big wire side when the control side is closing the relay (power on).
 
I did what you suggested, took the big (glowplug wire) off the relay, got my buddy to turn the ignition switch to pre heat, and then when the relay clicks I have continuity.

grounding to the battery confuses me because of the 24v setup, so I found a good ground on the motor, I know it is a good ground by putting the postive on the battery and then when the multimeter gets the 12v reading I found a good ground correct?

regardless if the relay is clicked on or off, I don't get a power reading on either post on the relay itself, but it clicks over, how is that possible?
 
So there is no 12v or 24v on the relay on either side when the wires are all connected?

There should be some fusible links at the battery terminal. They'll be on the battery positive terminal that supplies power to the truck. My bet is that one of them is bad.

They DO NOT look like fuses. They look like wires and they can be broken without looking like they are broken. Ohm them out or measure for 24v between the engine block and the end away from the battery for each one if your truck is 24v and 12v if your truck is a 12v. I was of the impression that all Canadian BJ70's were 12v (dual battery) but I could be wrong.
 
I guess I was wrong then! At least my BJ60 is 12v!
 
it sure would be nice, to rig up a button and just scrap this superglow BS, if anyone has done this on a 24v truck I would love to know how, that way I coudl put the momentary switch somewhere in the dash so it would be a good anti theft device...

please help....

I have the toyota manual here now and it isn't helping... I've checked everything and nothing has power, but the relay and resistor work like they are supposed to
 
Eric,

Essentially there are four wires connected to the glow-relay.
Two FAT and two smaller.
One of the FAT wires should have current all the time, at least from the moment you put in the ingition-key and switch to 'ON'. Let's call this one 'A'.
The other FAT wire connects to the glowplug-terminal on the engine.
Call this one 'B'.
Then the two small wires.
One has only current the moment you glow and the relais clicked. Call this one 'C'
One connects to the chassis (ground) and you shoulg never find any current on this one. Call it 'D'.

From previous postings I've read that, if you switch to glow, the relay clicks. Correct?
If you don't hear the relay click when switching to glow, look for voltage present on the terminal of 'C'.
Is it present? No click? Disconnect 'D' and put the grounding of your measuring-tool from body (chassis-) ground to the connector of wire 'D'. You should find the same reading as previous (when connected to body (chassis-) ground). If not, this wire 'D' is damaged.

You also measured 24V on the terminal where wire B connects to, when switching to 'glow'?
But have you also measured with the wire connected?
Because there is a possibility that you find voltage but that there is virtually no current flowing.
Test for voltage on wire B connected to the relay and ignition switched to 'glow'
Do you still have voltage? If not or extremely low, go to the terminal of wire 'A'. What's the reading on this? If still 24V (or thereabout) the relay is shot. If not, 'work' your way towards the batteries. There must be a bad connection somewhere.

If you still have voltage at the 'B' connection when glowing, work your way towards the glowplugs. If you even find voltage on the glowplugs and you are sure they are not glowing, there's only one thing left: glowplugs are gone (overglowing during previous attempts?)
The only way to check this is by disconnecting the connection that leads from plug to plug.
Then switch the meter to OHM and measure from glowplug-top to engine-ground. You should find a small value. Just a few ohms, but your meter should not indicate infinitive resistance, most of the time indicated by a '1' (one) in the display.
If you find a value of something like 2-5ohms, you should be fine.

If you think the glowplug(s) are gone, take them out and check them by connecting them to a batterie (12V is fine) VERY VERY shortly (1 (one) second max).
IT WILL SPARK !! If it's doesn't spark chanches are big that plug is gone, but check carefully (don't burn yourself!!!) or it has heated up a littlebit. If not connect once more, but a bit longer (2 secs) Check..
not warm....3secs etc. If you feel no heat at 5 secs or so......that plug realy is dead.

Well it's quite a story but I hope this is of some help.
 
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I think it is a fuse/fuseable link or something... even before the relay itself. but the relay does click, and when it clicks I get continuity on the two posts.... but there is no power on either post.
 
The power that makes the relay "click" comes from the ignition switch (wires "C" and "D" in Ron R's description) so that is OK since you can hear the relay click and measure continuity across the large wires from the relay.
Wire "A" in Ron R's description is ALWAYS hot. It doesn't need the key. If there is no power on it you have a fusible link or disconnected wire problem between there and the battery.
Wire "B" is ONLY hot when the relay is closed. The relay is normally open unless the key is in the "Glow" position AND the timer has not timed out.
Have you found the fusible links yet? There are within a couple of inches of the positive battery post (that's the post that measures 24v between ground and the post). They are usually enclosed in a small plastic box or something similar.
 
Yeah,
Cruiser_guy is right.
According your answer the fusible link is gone or the wire got damaged.
Switch your measuring tool to voltage (200V =) and start checking from the + stud of the batterie (one pin of the testtool to ground the other one to + ) and work your way from the batterie. There is a point where there are more then one wire connected to the batterie.
Check each one of them, one by one.
Shortly after 'leaving' the batterie there must be a point where there is no voltage anymore. Then you have found the fusible link.
If there still is voltage for some distance, then there must be a break in the wire.
Check the loom for damage! In any case. Also when the link is gone. There is a reason it has melted. You may have created a short somehow, causing the link to open -as it should - , but there can be damage to the loom/wire as well, creating a short.

have fun:doh:
 
mine is an 86, I herd somewhere that all the 70's were 24v my mistake....

Okay, so it has to be wire A... I don't see it coming off the battery at all... I am going to have to start tracing this wire back from the relay, thank you for all the help guys...
 
No doubt the wire is part of the loom (grouped with other wires) at the battery itself. You will certainly find a group of fusible links at the battery post. Check them all as one is very likely broken.
Usually they only fail due to excess current but it is also possible that it is simply brittle and broke. That's what happened to mine and I simply bought a new one at the dealer. You may want to do that too if you feel overwhelmed by tracing wires.

At the battery terminal that feeds power to the truck you will find a large cable that goes to the starter as well as several smaller wires, most protected by a fusible link. On my truck the fusible links have a plug on one side and use a terminal strip on the other. Check for power coming in as well as going out.

Post up a picture of your positive battery terminal connections and maybe we can guide you a little better.
 
Eric, they sell fusible link material to make your own link at Napa, I have seen it there on the shelves.
 
brownbear said:
Eric, they sell fusible link material to make your own link at Napa, I have seen it there on the shelves.
Click to expand...

Yep, but what amp rating does he need?
 
cruiser_guy said:
Yep, but what amp rating does he need?
Click to expand...

ah ha, I dunno.

But it is the 1.0 y fusible link?? In the FSM it shows it as this one.

If your hard pressed I can do the math for it. To make your own with a napa one.

It does show in the EPC, so if you need the part number and toyota doesn't have it....

Off the cuff, I would say it around 30 amps. Max 50. so I would try 30 first and if it blew then work up. But I could figure out the draw. if needed.
 
I try to get the least amount of stuff from toyota as I possibly can, mainly just because of the price... This truck is breaking me, usually wiring problems I would take to someone, but I'm broke, that's why I'm biting the bullet and doing it myself, but I really know nothing... You guys have been a great help already....

There are 3 wires coming off the - post on the LH battery, I know 2 of them are for headlights, as I've had to fix it before...

something about this 20 year old wiring, scares me a bit...

good thing this old beast is mechnical


thanks a bunch

An amp reading for that fusible link would be great, thanks for all you help

Eric
 
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