MEP002 no power to starter solenoid

[johnnybgoode]

Just replaced the engine on my MEP002A and have run into a problem with the new engine starting.
It will not even attempt to engage the starter with the main start switch, though the fuel solenoid and pumps will engage with the switch.
If I apply voltage to the starter solenoid contact while holding the switch to START then the machine starts and runs normal (but makes no power, but one problem at a time).
I have bypassed the oil pressure switch to get it to start when I jump it, but even with the bypass the START switch will not power the start solenoid, so I think that the oil pressure switch will need adjusted once I get it to start reliably, but I am trying to fix one problem at a time.
I have the manuals and have reviewed the system description and troubleshooting sections but do not see anything relating to my condition.
To recap,
- starter solenoid works as it should and engine starts and runs when jumped, with main switch held to START position
- main start switch will not provide start voltage to the solenoid
I'm sure it's going to be something simple, but any suggestions would be appreciated.
Thanks guys,
Patrick

 

[Dock Rocker]

The TM’s have a pretty good troubleshooting section on the K1 relay. The A1/K1 is where the signal comes from to go to the starter relay.




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[jbayer]

1.) Did the Old starter engage/crank?
2.) Is it the same starter, or did the starter come with replacement engine?
3.) Did the replacement engine run before? is it new, or used?
4.) background, did it run before, why replacement engine, etc.
5.) Did you verify your wiring/connections?

 

[johnnybgoode]

Thanks for the replies!

I'll look for the K1 section in the manual.

The old starter did engage and start the old engine, which I ran for a couple of years, until it developed a nasty knock. I will eventually tear it down and rebuild the old engine, but the price was right on this remanufactured replacement engine so I opted for the "simple" swap. I had swapped the style I starter for a style II, which worked much better than the original one, so I made the same swap (with my known good starter) on this engine when I initially ran into the no-start condition.

My son and I (11-years old) tagged all the connections we took off, as I am teaching him to work on diesel stuff in preparation for our rebuild of our Perkins-equipped Massey Ferguson tractor. They are all back where they should be.

Basic question is does anyone know how power could get from the START switch to the fuel pumps and fuel solenoids but not to the starter, with the oil pressure switch bypassed?
I'm out on the road now, but think my next step will be to run the continuity tests given in the book for switch S1 - perhaps one section (the starter control contact) of the switch has failed, though I've read they're usually not problematic.
Thanks again!

 

[Dock Rocker]

The signal from S1 goes through A1/K1 to the starter solenoid. If K1 isn’t right then it will not send power to the start side of the starter solenoid.


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[johnnybgoode]

Thanks Dock Rocker. I'll verify that the switch is actually telling the K1 to apply voltage first. If it is, and no voltage is making it out of K1 then that will give me somewhere to start.

 

[Guyfang]

The oil pressure switch is not adjustable. You need to look at the schematic.

 

[johnnybgoode]

I'm not following what you're answering in that last statement. I know it isn't adjustable - I bypass the switch that drops the starter offline while running to allow the flashing of the coil, if necessary. This switch, if set improperly, has given guys starting problems in the past and I'm eliminating items one at a time to narrow down my possible issue.
Thanks for the input.

Edit - I see I incorrectly mentioned bypassing the oil pressure switch - perhaps this is what you were referring to.

 

[Guyfang]

Just replaced the engine on my MEP002A and have run into a problem with the new engine starting.
It will not even attempt to engage the starter with the main start switch, though the fuel solenoid and pumps will engage with the switch.
If I apply voltage to the starter solenoid contact while holding the switch to START then the machine starts and runs normal (but makes no power, but one problem at a time).
I have bypassed the oil pressure switch to get it to start when I jump it, but even with the bypass the START switch will not power the start solenoid, so I think that the oil pressure switch will need adjusted once I get it to start reliably, but I am trying to fix one problem at a time.
I have the manuals and have reviewed the system description and troubleshooting sections but do not see anything relating to my condition.
To recap,
- starter solenoid works as it should and engine starts and runs when jumped, with main switch held to START position
- main start switch will not provide start voltage to the solenoid
I'm sure it's going to be something simple, but any suggestions would be appreciated.
Thanks guys,
Patrick

You wrote it, not me.

Go to -12 TM. PDF reader page number 51. Look at the S1. Pin 28, on the S1 is the start sequence. Turn the S1 to the start position. Measure for 24 VDC at pin 28. Do you have it? If no, then S1 is bad, or hooked up wrong. If you have 24 VDC at pin 28. then go to TB5-9. Measure there for 24 VDC, with the S1 in the start position. If no voltage is present, then check the wire number P66D16, that runs from pin 28 on the S1 to TB5-9, to see if it is whole. If you have 24VDC at TB5-9, then check at K1 A1-1, to see if you have 24VDC, with the S1 in the start position. If voltage is not there, check wire number P66E16, the wire that goes from the TB5-9 to the K1 A1-1. If voltage is present at K1 A1-1, then hold your hand on the K1 and switch S1 on and off a few times. Feel it engaging? If not, check K1 A1-2 wire number P55P16, the wire from K1 A1-2 to ground. If all the wires are good, and the relay is not engaging, its bad. Get that far and see how we are doing.

 

[johnnybgoode]

And you are correct - I did mis-write that. I was referring to the switch to dis-engage the starter. Sorry. Thanks for the guidance - I'll check that section out tonight on my way to London - unfortunately I'll not get to do anything but read until I get home this weekend.
Thanks again!

 

[Dock Rocker]

You wrote it, not me.

Go to -12 TM. PDF reader page number 51. Look at the S1. Pin 28, on the S1 is the start sequence. Turn the S1 to the start position. Measure for 24 VDC at pin 28. Do you have it? If no, then S1 is bad, or hooked up wrong. If you have 24 VDC at pin 28. then go to TB5-9. Measure there for 24 VDC, with the S1 in the start position. If no voltage is present, then check the wire number P66D16, that runs from pin 28 on the S1 to TB5-9, to see if it is whole. If you have 24VDC at TB5-9, then check at K1 A1-1, to see if you have 24VDC, with the S1 in the start position. If voltage is not there, check wire number P66E16, the wire that goes from the TB5-9 to the K1 A1-1. If voltage is present at K1 A1-1, then hold your hand on the K1 and switch S1 on and off a few times. Feel it engaging? If not, check K1 A1-2 wire number P55P16, the wire from K1 A1-2 to ground. If all the wires are good, and the relay is not engaging, its bad. Get that far and see how we are doing.

These directions look very familiar! Thanks again for all your help Guyfang


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[Guyfang]

The switch you mean is S7. We will get there, if the above post hasn't worked.

 

[Guyfang]

These directions look very familiar! Thanks again for all your help Guyfang


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Thats why its called Troubleshooting. Start at the start, work your way forward.

Your very welcome!!

Is this a conversation thread?

 

[justacitizen]

Thats why its called Troubleshooting. Start at the start, work your way forward.

Your very welcome!!

Is this a conversation thread?

Guyfang. you are working on getting another "Attaboy" award.

 

[Guyfang]

Beer!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! That's enough!!

 

[jamawieb]

Did anyone think about the starter lock out. If its a new engine, maybe its not adjusted correctly and if the leads in the lock out are not touching, the unit will not start.

 

[Guyfang]

Thats S7, starter lock out.

 

[johnnybgoode]

Update - had a few minutes to look at it again today. Traced S1 power through to K3. I'm getting the signal to pull K3 in and it has power on the upstream side of the relay but downstream going to the starter solenoid is not ever seeing voltage. I leave again tomorrow for a few days but when I return I will pull that relay apart and see if the contacts are perhaps corroded. Cycling it multiple times didn't make any difference, though I could feel the K3 actuate when I engaged S1 in the Start position.

 

[johnnybgoode]

no progress

Second update - So I pulled and verified that K3 is indeed a good relay. The problem is that it is never being drawn closed. With the Start switch engaged I have 24V on both (K3-X1) and (K3-X2), the control side, but the relay does not close, so I think it must not have a good path to ground on the other side of the control circuit. In the diagram I see what appears to be the CR-1 diode in series with the control side. Perhaps this is open. I have already jumpered S7, thus bypassing it entirely, until I get the unit to start. Then I'll worry about whether it is adjusted properly.

I should add that when I initially set the batteries in place after the motor swap, and while they were hooked up, I bumped one and the terminals touched and arced. I think I'm going to find that that did something to one of the components in the DC side of the circuit, but we'll see.

As always, thanks for reading and any help is appreciated.

 

[johnnybgoode]

Success, finally

After more investigating.
When Start switch is engaged one side of S7 (P59A16) has 24V but no voltage is showing on TB4-12, 13, and 14. It would seem to me that with my jumper bypassing S7 these terminals should have 24V. No?

If I run a jumper wire from K3-X2 to TB4-12 and then engage the start switch she starts! Would the pros agree that this looks like I have what could be a broken wire somewhere between X2 and TB4-12? The only thing in the circuit is a plug or two and the S7 switch, which I have jumpered.

*************

I'll close here, because I just found my problem. S7 is a three wire plug with only 2 wires used. I picked the two wires to jump that correspond with the two wires going in on the back of the plug but apparently they either have the wires swapped internally or the plug has rotated somehow because after writing the above sentence I wondered if perhaps the jumper was in the wrong position. I swapped it to another set of the S7 plug terminals and it works as it should. Learn something new every day...

Thanks for the assistance to those who helped. I'll phone back in if I can't get it to make power, but I bet that after adjusting the S7 it will flash and make power as it should.

Patrick