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Old 11-25-2021, 12:40 PM   #1
Mini-Skoolie
 
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Question about Starting Solenoid Thomas 2001 HDX

Hey folks,

I have a Thomas 2001 Saf T liner HDX and I have been busy working on the inside but I may have to move it soon.

I have been having trouble with starting it from the ignition.

The starter solenoid is usually mounted in the rear electrical box, when I was doing some work it got removed from there and is hanging loose.

My question is, on this bus, is the solenoid grounded when it is bolted to the rear electrical box?

If I run a wire to the 4th pole of the solenoid to the ground terminal in the electrical box then it will start on the key, however, I am a bit confused as this 4th pole shows 12v when the ignition pole is powered?

The 4th pole is connected to a wire that goes to the rear electrical box and the wiring diagram lists this fused wire as 'ether start signal from solenoid'

I am a bit confused. Do I have a bad ground? Is this wire 'ether start signal' supposed to arm the solenoid in some way and something is preventing this?
I don't think I want to add a ground wire just to make it start from the key. Any help or advice much appreciated.

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Old 11-25-2021, 12:58 PM   #2
Bus Crazy
 
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It sounds normal. The terminal you mention should be grounded. The case on the solenoid should not normally provide a ground, if there are 4 terminals. Just to clarify, there will be two large terminals...one from the battery and one to the starter. The other two smaller terminals are for the coil, which closes the contacts between the large terminal.

If you skip to the 15:00 or so mark in this video, I start troubleshooting a solenoid like that and a bit later I describe what the terminals do. That might help?

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Old 11-25-2021, 09:15 PM   #3
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Perfectly normal to read 12 volts on the open terminal with the key on. You're just reading through the coil.
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Old 11-27-2021, 09:44 AM   #4
Mini-Skoolie
 
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Hey folks,

Thanks for the info.

That video was a fun watch!

I got things working again, I bought a new solenoid and grounded it out and now bus works on the ignition.

New problem, now none of the temperature gauges on the dash work and the display says ' no data '

I will go look for wires not connected and see if anything is obvious.

Thanks again
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Old 11-30-2021, 04:55 PM   #5
Mini-Skoolie
 
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I managed to get the cluster to work again. I cleaned all the grounds and major terminals all over the bus, on the engine, in the electrical boxes, and up front where it comes into the bus.
I did that and also took the cluster out and unplugged the connectors and put them back in and all is well again on that front, mileage shows and gauges work.

I haven't used this bus for a year or more and the last time it was driven it wouldn't rev very high or go more than 10-15mph.

Along with the electrical issues I also fixed a section of exhaust pipe that was missing between the turbo and the silencer/filter.

When I first started the bus up after fixing this it would rev all the way up quickly and I believe I could here the whooshing of the turbo. I thought I had fixed it!

Anyhow, after a minute or so it was back to revving very slowly up to 1500rpm max. I switched it off and called it a day.

Where should I start to look? It obviously was happy for a minute but something has derated it. I don't have any check engine lights on the dash and it starts without any hesitation.

Should I be looking at simple things like fuel and air filter? I feel like not though as it did rev to max fine at first.

Oh also, when I press the accelerator pedal I can hear a relay click in the front.

I do have CAT ET(it is a 3126 engine), but I have no idea how to use it or what to be looking for.

I am really low on funds, I might have to move this thing very soon, and I love figuring out problems, have tools and not afraid to get dirty or stuck in. If anyone has any information about where to look next, or can guide me on what to look for on CAT ET I would be more than extremely grateful.

Many thanks again

Daley
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Old 11-30-2021, 08:39 PM   #6
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Quote:
Originally Posted by rossvtaylor View Post
It sounds normal. The terminal you mention should be grounded. The case on the solenoid should not normally provide a ground, if there are 4 terminals. Just to clarify, there will be two large terminals...one from the battery and one to the starter. The other two smaller terminals are for the coil, which closes the contacts between the large terminal.

If you skip to the 15:00 or so mark in this video, I start troubleshooting a solenoid like that and a bit later I describe what the terminals do. That might help?


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