Glad to be here

[Randi]

Hello, I’m new to this platform, thanks for having me. Bus conversions have been my life’s work and livelihood for the past 14 years. I’d only worked on shuttle and school buses until I recently purchased a 2003 gillig transit bus with a Cummins motor. My partner and I have been working on this particular bus for 6 months and are near completion. It has never had any issues starting or driving until a couple of weeks ago when the brutal cold hit MN. We had put anti gel fluid in with the diesel before temps plummeted thinking this would save us from gelled up lines and filters. The first day of extreme temps the bus started dying every few minutes (check engine light would come on and high idle had been on). The following day and every day since it won’t even try to turn over, lights and accessories come on but start button does nothing. We have taken the batteries into our shop most nights to warm them and charge them up, we have replaced the starter, the starter fuse and the starter relay, nothing has changed. Our next idea is the fuel filter and fuel water separator. Also, all fluids are topped off, however when the check engine light began coming on they hadn’t been, oil was just under a quart low and coolant was a half gallon low. Maybe because they were low something needs to be reset? Maybe someone here knows a lot more than me about gilligs, I have very limited knowledge. Please throw some pearls of wisdom my way if you can! Thanks

[Jolly Roger bus 223]

sorry
i cant help with anything gillig but basic mechanic stuff?
does your starter have the start solenoid built onto it or is it a seperate solenoid under the hood somewhere? or is the the start relay you refer to.
have you tested for voltage and or jumped out the start switch to see if you get it to turn like that.
have you cleaned all the ends of your battery cables including the chassis ground.
what voltage does your batteries read?
have you had them load tested?
there are gillig owners here that can give more specific advice just be patient and let them catch up and find your thread

[Randi]

Thanks for responding! The starter relay was apart from the starter, located in a separate starter relay box. The batteries are 24 volt, connections have been cleaned. My partner has been testing wires, the small wire going to the starter doesn’t seem to have power (ignition wire?) Thanks for the heads up, and taking the time to read this!

[HamSkoolie]

When the symptom is "engine wont turn over" the problem IS NOT fuel filter, fuel, or lines. Nor is it past status of lubricant, coolant, or other fluids. It is going to be dead batteries, an electrical fault in the circuitry between batteries and starter (including computer modules), or a properly working circuit that disables the starter when a certain condition is present (such as an open escape hatch indication). Bus manufacturers use different methods to create safety circuits so you need to figure out how your manufacturer does them.

You've replaced the starter and recharged the batteries but have you done any diagnostic testing?
First test, load test on the fully charged batteries to ensure they have sufficient power to start a bus. Simple voltage tests can find a bad battery in some conditions (bad cell) but voltage alone can't tell you how healthy the battery is.

For the starter, the first check should have been (and still should be) testing for a starter solenoid "start" signal when the ignition is key or button is actuated to the "start" position. Odds are, having replaced the starter, that the signal is not present or is insufficient to actuate the solenoid. However, brand new parts (and rebuilds) can be bad right out of the box so the test shouldn't be bypassed.
Whatever you do, don't just throw parts at it. That gets expensive very fast and then you have a whole bunch of potential faults from all the disturbances created when replacing those parts.