M1078 start issue

Had problems starting our M1078. Bypassed red start button with another start button wired directly to the frame mounted start solenoid. After the first start, the thermal switch on the starter prevented additional starts. As suggested in a previous thread we tied the two white wires for the thermal switch together. That seemed to work and it also allowed us to use the red start switch again. Then after running the truck hard for a day, it would not start again until it cooled down. We ran a ground wire from the frame mounted start solenoid to ground as suggested in another thread. Now it starts, but not with the red button, back to our second start button wired to the solenoid. I'm wondering if we need to reattach the white wires to their original position in order for the red start button to work again. Are the two fixes working against each other. Thanks.

cheesehead dave said:

Had problems starting our M1078. Bypassed red start button with another start button wired directly to the frame mounted start solenoid. After the first start, the thermal switch on the starter prevented additional starts. As suggested in a previous thread we tied the two white wires for the thermal switch together. That seemed to work and it also allowed us to use the red start switch again. Then after running the truck hard for a day, it would not start again until it cooled down. We ran a ground wire from the frame mounted start solenoid to ground as suggested in another thread. Now it starts, but not with the red button, back to our second start button wired to the solenoid. I'm wondering if we need to reattach the white wires to their original position in order for the red start button to work again. Are the two fixes working against each other. Thanks.

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[h=3]M1078 starting[/h] Started by cheesehead dave, 12-29-2016 21:36

Since you already have a thread on this problem you should keep using that thread , that way people trying to help you have all the information as to the problems and attempts at fixing in one place.

Have you had the starter tested ? Not wanting to start hot but will when it cools down is a sign of a bad starter.

My suggestion is to follow the "engine does not crank" troubleshooting logic tree in TM9-2320-365-20-1. You can skip sections that check the starter motor and auxiliary starter solenoid, as you know these are good. The fixes you have already applied have prevented future problems and are unrelated to your unresolved issue. You are looking for wiring connections/contacts that are intermittent due to corrosion, damage, looseness, etc.

Found a 5 pin relay in the K1 start relay slot. Should have been a 4 pin relay. Installed 4 pin relay and it fired right up with the red button. We also did the mod on the starter to bypass the starter thermal switch (P81). Drove the M1078 for an hour. Stopped and started the engine several times. Works as advertised. Thanks for all the help. One more question. We would like to put a battery tender on the unit. Any ideas how to wire that in as it is a 12/24 volt system with 4 batteries. Thanks.

cheesehead dave said:

Found a 5 pin relay in the K1 start relay slot. Should have been a 4 pin relay. Installed 4 pin relay and it fired right up with the red button. We also did the mod on the starter to bypass the starter thermal switch (P81). Drove the M1078 for an hour. Stopped and started the engine several times. Works as advertised. Thanks for all the help. One more question. We would like to put a battery tender on the unit. Any ideas how to wire that in as it is a 12/24 volt system with 4 batteries. Thanks.

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If you want to do it "properly", get a NATO slave plug and then just plug the truck into the tender. That will save you having to pop the battery cowl every time you want to attach it. Otherwise, you can just get a 24V tender and just clip it on. I recommend the NOCO G26000.

Thank you. Sounds like a plan.