Starter won't engage...

[docsurf]

Hi all,

We've got a 2005 Thomas RE w a CAT C7. Haven't had issues, however...

When spring arrived I realized I hadn't hooked up the trickle charger after starting it the last time in winter and both batteries were toast.

We live in the sticks so it was a while before we were able to have them replaced from the CAT dealer in the city.

Put them in, put them on the trickle charger to top them off and went to start it....nothing. I mean the warning buzzer sounded, the intake heat light went off and that is the typical time to crank it up....turned the key over and nothing....

Any thoughts would be appreciated.

Doc

[BamaBus]

Since you only mention work on the batteries, I'm going to go with a blown fuse. Possibly an inline fuse in the battery compartment or an ignition fuse in the main fuse panel. Also check and make sure there are not any single wires that may have fallen behind the batteries and never got reconnected.

[sportyrick]

if you have an Allison the power is taken directly from the batteries, you didn't put a wire back on and the transmission is dead so no neutral switch to activate the starter.

[Jolly Roger bus 223]

the OP stated they had the CAT shop replace the batteries.
i know even the pro's aint perfect but the OP also doesnt say if they drove it home from the shop and has a problem once home or if it is still at the shop and the high dollar pro's dont know?
several things to consider depending on where it is at and who is working on it?
a shop that knows a customer brought a vehicle in just to replace the batteries then they see that as an opportunity because if they caint do that then they dont know what they have.
if the job was correct and the OP drove it home then they have a parasitic drain and should be disconnecting the batteries before they waste there latest investment.

[accomplished oaf]

Hi everyone,

I've only had my bus a couple of weeks. Batteries are good -- strong voltage on all three, everything works fine, including the wheelchair lift.

But the starter motor acts like the battery is almost dead. It tries to engage, but can't.

This is a sudden new behavior. Until today it always started right up without any trouble. Any suggestions? Does anyone know how to test the starter motor to see if that's the problem?

Details-- 2010 IC bus, MAXXForce 7 engine, Allison 2000 series transmission.

Thanks!

[sportyrick]

CABLES cables cables!

[accomplished oaf]

That's usually a good answer. Unfortunately all the cables are tight and clean -- No corrosion. Nothing lose. No voltage drops when I hit the starter.

It gives a brief series of short clicks, pause, a brief series of long clicks, pause, short clicks, pause, long clicks... etc. It almost feels like a diagnostic code of some kind.

[sportyrick]

that can still be a cable, they can look good and still be corroded in the connections. Solenoid? carefully jump from battery side of solenoid to the terminal that goes into the starter itself with one of the cables from jumper cables, the starter should spin. If so then suspect the solenoid, if not then it's time for a starter. This is dangerous because of the 3000 amps of current, eye protection, gloves, do NOT short to ground, be very careful grasshopper.

[ewo1]

Originally Posted by accomplished oaf

That's usually a good answer. Unfortunately all the cables are tight and clean -- No corrosion. Nothing lose. No voltage drops when I hit the starter.

It gives a brief series of short clicks, pause, a brief series of long clicks, pause, short clicks, pause, long clicks... etc. It almost feels like a diagnostic code of some kind.

You just might have clean tight connections on the battery but then there is also a chassis ground, actually bolted to the chassis not the battery, and another connection on the starter itself.

On my bus the ground wire from the battery, was loose and corroded where it was bolted to the chassis. it did the same thing you describe as what yours is doing.

So while the left eye is looking at the battery, tell the right eye to look at the other end of your connections.

also don't rule out a defective or loose wires on the key switch itself but more likely is you battery connections.

The fact that you see no voltage drop is because the starter is not pulling any current.

[accomplished oaf]

Thanks. I used to work with a 70 year old electrician. He taught me a healthy respect for amps! It's hard to make progress in this 105 degree Texas heat tho. I'll tackle it in the morning (if I can get up before the sky-furnace fires up...)

[accomplished oaf]

That chassis ground seems to be inside one of the frame channels next to the transmission. Gonna take some effort to get to that one. But thanks anyway. I've got some good ideas to follow now. I'll post an update when I get an answer.

[accomplished oaf]

After cleaning and re-tightening all the battery and starter connections, no difference. Voltage is still good, etc...

It turned out to be the gate-latch at the bottom of the rear emergency door. The door was not latched--as required for driving as a school bus--but the latch was not fully seated in the unlock position. It was open, but also loose. This disabled the starter. Millimeters matter. I had pulled the plug on the buzzer a few days ago, so there was no warning.

Anyway, thanks for all the advice. It was an adventure!