Electrical/Starting/Starter Problem

[Icy Fishy]

Hello All:

A few months ago I imported a RHD 1988 HJ61 from Japan to Northern MN. Things here got cold recently and as a result I learned of some weak points on my vehicle but I'm focusing on just 1 issue in this thread.

The batteries I have are new but too weak for the cold. They were installed by the importer before I took possession. A few days ago the temps were well below 0, the truck did not immediately start and the batteries were drained by the starting attempt. I was only able to crank briefly before they died. I attempted to jump the vehicle with a Yesper 12v/24v jump-starter pack. I followed jumping instructions found on these forums and attached the positive clamp to the positive post on the driver's side and the negative clamp to the negative post on the turbo side. The jump pack does not recognize that it is hooked up to the batteries, so I have always needed to use the override feature. I started cranking (vehicle not started yet) and then attempted stop and turn the key back to the off position. The key was stuck and it kept cranking. I jumped out fast, disconnected the positive clamp, and it stopped cranking.

I then disconnected the batteries from the truck and put chargers on both batteries. A few days passed and the temps here are now in the low 30s. Hooking the batteries back up to the truck I used this order: 1) positive post on driver's side battery, 2) positive post on turbo side battery, 3) negative post on driver's side battery and 4) negative post on turbo side battery.

When the connection for the last post touched it sparked a lot and the starter started cranking. There was a bunch of sparks and the connector ring was instantly melted/stuck to the post, although I was able to pull it off quickly.

What's my next move?

 

[Icy Fishy]

Also, the key was in the off position at the time of the issue described above.

 

[duncanrm]

The starter relay sounds like its fused ON.. It'll be mounted near your airbox on the right hand side inner fender.

My immediate diagnostic step would be to pull off the small trigger wire on the starter and see if the problem resolves:

• If its still cranking after the starter trigger wire is removed when the batteries are connected then the starter itself is faulty
  • The solenoid may be fused on
• If it doesn't crank with the starter trigger wire disconnected then I'd start investigating the starter relay and its input
  • The starter relay contacts may be fused on
  • The starter relay may have a permanent positive on its input activating it
    

 

[Eurasiaoverland]

I think Duncan's on the money - I had exactly this problem in a Hilux and it tuned out that the starter relay was melted closed. And as the relay is directly wired to the battery, there is no switching involved if the relay is stuck closed.

In case you are new to diesels, there will be a pre-heat cycle on the 12H-T's intake heater which at such low temperatures will draw a huge current. If you don't wait for the cycle to finish (glow light off), then this in combination with the starter will place a huge load on your batteries.

 

[Icy Fishy]

The starter relay sounds like its fused ON.. It'll be mounted near your airbox on the right hand side inner fender.

My immediate diagnostic step would be to pull off the small trigger wire on the starter and see if the problem resolves:

• If its still cranking after the starter trigger wire is removed when the batteries are connected then the starter itself is faulty
  • The solenoid may be fused on
• If it doesn't crank with the starter trigger wire disconnected then I'd start investigating the starter relay and its input
  • The starter relay contacts may be fused on
  • The starter relay may have a permanent positive on its input activating it

View attachment 4049564

Thanks, that’s helpful. How do I identify the tigger wire?

 

[Icy Fishy]

I think Duncan's on the money - I had exactly this problem in a Hilux and it tuned out that the starter relay was melted closed. And as the relay is directly wired to the battery, there is no switching involved if the relay is stuck closed.

In case you are new to diesels, there will be a pre-heat cycle on the 12H-T's intake heater which at such low temperatures will draw a huge current. If you don't wait for the cycle to finish (glow light off), then this in combination with the starter will place a huge load on your batteries.

I am new to diesels, in case it’s not obvious. That’s an interesting point on the draw from the heating element. I did wait for the light to turn off before cranking. Given the feedback I’m getting here, I’m concerned that my use of the jump pack on the “override” setting fried the relay.

 

[Eurasiaoverland]

Thanks, that’s helpful. How do I identify the tigger wire?

The relay has two pairs of wires; the main switched circuit which will be two thicker wires (most likely black with a red trace and white) and the trigger circuit will two thin wires (white with a black trace, which is the negative/ground, and white). If you put 24 V across these two wires you should hear the relay click closed. If there is no noise, the relay is bad and needs to be replaced.

 

[Eurasiaoverland]

I am new to diesels, in case it’s not obvious. That’s an interesting point on the draw from the heating element. I did wait for the light to turn off before cranking. Given the feedback I’m getting here, I’m concerned that my use of the jump pack on the “override” setting fried the relay.

An electrical device will take the current it needs; having a large capacity jumper will not oversupply it with current. The relay was probably bad from moisture/corrosion. Or there is a short or bad ground in the wiring of the starter which draws too large a current. A bad relay is far more likely IMO.

 

[Icy Fishy]

Okay, the problem is not the starter relay. I installed a new relay and as soon as the batteries are connected it starts cranking. The key is not in the ignition and the ignition is in the off position.

I disconnected the battery, inserted the key, turned it on and off a few times, and generally wiggled the key around. When I reconnected the batteries it still immediately stared cranking.

What should I be looking at? Possibly just order a new ignition switch?

 

[Eurasiaoverland]

Ok, interesting. Try unplugging the ignition switch (under the steering column, it will be a rectangular connector with most likely 6 positions, but probably 5 wires. Then connect the batteries and see if it does it again. If the problem goes away, the ignition switch is the culprit. In not, most likely it's a wiring fault.

 

[AirheadNut]

It's been a while since I had a Toyota starter apart, is it possible that the starter solenoid is fused closed instead of the starter relay? I've had them stick open, but I suppose it could stick closed if the plunger got gummed up with old grease and the copper contacts fused under load.

 

[duncanrm]

Are you using a Test Lamp to diagnose this? Its the absolute most essential tool to own when working on electrical systems in an old Landcruiser. Its a more important tool than a multimeter.

I'd have this diagnosed in about 2mins flat with a test lamp.

Remove the high current lead from the starter, connect your batteries. Probe the Trigger Wire on the starter motor and see if your lamp lights up (clamp connected to earth). If it lights up, start working your way backwards - does the output of the Starter Relay light up the lamp? Does the input to the starter relay light up the lamp? With the high current lead disconnected and the batteries reconnected do you hear the starter solenoid clunk when the batteries are connected?

As @AirheadNut has noted, if the starter still self activates with the trigger wire disconnected then the starter is faulty internally.

 

[Icy Fishy]

I do have a test light and a digital multi-meter. Following the holidays I finally found time to try and sort these issues.

Per @Eurasiaoverland's suggestion, I unplugged the connector for the ignition switch under the steering column. As noted, it has 6 positions but only 5 pins. The started motor did not crank when I connected the batteries. However, it did make a disconcertingly large spark sort of welded/stuck the terminal to the battery post the instant it made contact. I immediately pulled it off.

Using the mutli-meter I checked the continuity between the different pins in the ignition switch connector as described in the FSM. The relevant page is attached this post. Everything checked out property except the connection between pins 3 and 6 when the key is in the "on" position. The connection was intermittent and slightly wiggling the key affected whether there was continuity.

Given the problem (starter cranks if batteries are connected even with key in "off" position) I was expecting to find continuity between some pins when the key is in the off position. What thoughts do people have about this? Are there additional diagnostics I can do on the ignition beyond what is in the attached FSM page?

At this point, I intend to start following the advice from @duncanrm and @AirheadNut, and try to identify any problems beginning at the starter motor and working back toward the batteries. But given that the starter did not crank with the ignition unplugged, I feel like the problem is with the ignition switch and related wiring.

 

[duncanrm]

But given that the starter did not crank with the ignition unplugged, I feel like the problem is with the ignition switch and related wiring.

Absolutely.. that's solid progress. You've now localised the problem very conclusively to the ignition switch and related wiring. No need to start back at the starter motor now.