Miller trailblazer 280nt

[bulldog77]

We have a trailblazer 280nt with a onan engine on one of our tool trucks. For awhile it could only be started if it was jumped and you left the cables on between the truck and welder. Now it came in and it wont crank over at all. We have replaced the starter, switch, and voltage regulator. We have power to one side of the starter but nothing after that. Any direction would be appreciated.

[Tryagn5]

jump starting...

We have a trailblazer 280nt with a onan engine on one of our tool trucks. For awhile it could only be started if it was jumped and you left the cables on between the truck and welder. Now it came in and it wont crank over at all. We have replaced the starter, switch, and voltage regulator. We have power to one side of the starter but nothing after that. Any direction would be appreciated.

hopefully you did not burn up the board by jump starting it. Trailblazers can not be jump started or boost started. It frys the control board. Cruizer can tell you which one it smokes. As for the starting issue. Likely the plug between firewall and engine connector or bad igntion switch. Ohm starter wire off the igntion switch to the starter solenoid motor on the engine.
kevin

[H80N]

hopefully you did not burn up the board by jump starting it. Trailblazers can not be jump started or boost started. It frys the control board. Cruizer can tell you which one it smokes. As for the starting issue. Likely the plug between firewall and engine connector or bad igntion switch. Ohm starter wire off the igntion switch to the starter solenoid motor on the engine.
kevin

+1 Jump starting a TrailBlazer is a NoNo.....

[bulldog77]

I have checked continuity on all the wires from the switch to plug to switch and all tested good. The guys tell me they had to jump start it most of the summer. The minute you took the jumper cables off it would die.

[H80N]

I have checked continuity on all the wires from the switch to plug to switch and all tested good. The guys tell me they had to jump start it most of the summer. The minute you took the jumper cables off it would die.

Among other things that can be damaged or destroyed by jump starting a Trailblazer is the monolithic voltage regulator on the engine.. they are potted and therefore not repairable... so must be replaced when damaged by the huge current inrush when jump starting..

Pic below

[H80N]

Among other things that can be damaged or destroyed by jump starting a Trailblazer is the monolithic voltage regulator on the engine.. they are potted and therefore not repairable... so must be replaced when damaged by the huge current inrush when jump starting..

Pic below

When you blow that regulator the engine will not be able to maintain a charge on the battery and will not be able to start on it's own..

[Tryagn5]

I have checked continuity on all the wires from the switch to plug to switch and all tested good. The guys tell me they had to jump start it most of the summer. The minute you took the jumper cables off it would die.

Ok i assummed you changed the battery. So change the battery if the unit only starts when it is jumped then clearly the battery is bad. You had previously stated it does nothing. Gotta figure if you did a starter you would also have checked for a charged battery. Now check the charging circiut. With the engine running you should have around 14 volts at the battery.
Kevin

[Tryagn5]

power on side of starter..

Also how much power to one side of starter..actual voltage...not a test light. If you have good voltage ie..11.5 or more when the unit is turned to the crank side you should see the same voltage to starter circuit solenoid wire..if not bad wiring or bad switch or discharged battery
Kevin

[H80N]

Ok i assummed you changed the battery. So change the battery if the unit only starts when it is jumped then clearly the battery is bad. You had previously stated it does nothing. Gotta figure if you did a starter you would also have checked for a charged battery. Now check the charging circiut. With the engine running you should have around 14 volts at the battery.
Kevin

FYI... if that regulator is blown.. it will discharge even a brand new battery overnight... when that little zener diode in it pops it will allow a small but steady leakage to ground....
Even if it seems to be charging to a nominal 13.8 volts while running .... it will drain the battery flat a few hours after being turned off..

[bulldog77]

The starter, switch, and regulator all have been replaced. 12.86 volts from battery and I also have switched out batteries.

[Tryagn5]

The starter, switch, and regulator all have been replaced. 12.86 volts from battery and I also have switched out batteries.

Clearly your wiring from the igntion switch to the starter solenoid...ie the little wire which engages the starter solenoid coil is bad or is nearly broken. Test the wire for voltage with it hooked to the solenoid, and unhooked. If you get voltage with it unhooked then the wire is nearly broke or there is heavy corrision in the plug. Have you tried jumping the solenoid to see if it starts?
Kevin

[bulldog77]

It does start and run if I jump the starter. Next I guess is to look for broken wires?

[Tryagn5]

It does start and run if I jump the starter. Next I guess is to look for broken wires?

Yes. Do what i told u to do in my first post.
kevin

[bulldog77]

All the wires and plugs check out ok. There is a diode, GT60-04f in line. I have checked that and it seems to be bad. Could this be all that causing it to not start?