2008 Thomas C2 MB306 Won't Crank

[Ifly4fun]

Bus has been in the driveway for 4 months. I'd occasionally start it and let it run for a while until fully heated. Never had an issue starting. Went to start it (after about a week since last time) and it won't turn over. Dash lights up fine, turn key and nothing. Eventually check engine and range inhibit lights come on.

When I turn the key, I can hear a relay click under the switch panel. Checked exit doors (alarms still work so I assume they're fine). There are some diag codes on the dash but not sure if these would inhibit it turning over:
ECU 128 SID 231
BHM 164 SID 022
BHM 164 SID 037

It has two batteries in parallel - I've never the charger on for a day, reads 12.6V at the dash. Is it possible I still have insufficient or bad batteries causing this? Anyway to isolate them as cause without buying new ones?

I've read "shorting the starter solenoid" to see if it'll crank - Any have info on where this is or exactly what to short?

2008 Thomas C2 MB306.

Thanks!
Jeff

[cadillackid]

thre codes seem to indicate a loss of communication between the transmission and engine controllers.. since the ECU and BHM give you codes it means those are likely powering up.. I would make sure the batteries are charged fully.. 12.5 is like OK but also time to make sure all the fuses are good for ECM, BHM, TCM.. might be labelled as engine, trans, body module.. I dont have a fuse panel layout for a freightliner in front of me to look at them..



usuaslly when I see comms loss it means one or modules failed to power up

[CHEESE_WAGON]

I know this sounds crazy, but you could try pouring Coca-Cola on the battery terminals. It's possible the terminals and/or posts have oxidized or corroded from sitting, and this can compromise the connection, preventing cranking. The Coca-Cola will dissolve the oxidation.

In my taxi days, I was asked by dispatch to check out another driver's vehicle because it wouldn't start. Everything had power, but the starter would not engage. Poured some Coca-Cola on the battery terminals and it fired right up. The terminals didn't even look corroded or oxidized, but apparently that was the problem.

[Jolly Roger bus 223]

12.6 is a weak for cold starting a diesel especially if was shut off halfway through a compression stroke.
i think the batteries need to be charged up two around 13.4 or better.
and or you can put a socket,ratchet and cheater bar on the crankshaft pully and try to rotate over by hand to clear the stroke it is in.
i would try these two things and as christopher says check your fuses and power to your modules before we explain how to jump the starter solenoid.
also find your starter solenoid and read voltage there it shouldnt be much lower than your battery reading and if it is then that could indicate an old or bad battery cable and yes the coca cola thing does work.
good luck

[cadillackid]

I should add that jumping the solenoid on a computer Diesel engine will not likely do much . The computer doesn’t turn on the starter for a reason. It’s possible that a simple wire or relay is bad but most likely the computer has disabled the starter because it knows the bus won’t drive correctly. Ie if no comms to the transmission on an allison with SEM enabled the trans will fail to do much more than operate in 1 gear or if it’s an MD3060 it will stay in neutral

[Danjo]

Originally Posted by CHEESE_WAGON

I know this sounds crazy, but you could try pouring Coca-Cola on the battery terminals. It's possible the terminals and/or posts have oxidized or corroded from sitting, and this can compromise the connection, preventing cranking. The Coca-Cola will dissolve the oxidation.

In my taxi days, I was asked by dispatch to check out another driver's vehicle because it wouldn't start. Everything had power, but the starter would not engage. Poured some Coca-Cola on the battery terminals and it fired right up. The terminals didn't even look corroded or oxidized, but apparently that was the problem.

Tab or Diet Rite if you got it. The sugar can also cause connection problems. Baking soda in water is king though in my opinion.

[Ifly4fun]

Thanks, I guess I need to fine the TCM fuse. I was able to start the engine by shorting the starter solenoid and it started easy and strong so at least I know my batteries are good. I took it for a spin and the CEL/Range Inhibit remained lit and it felt like it wasn't going over 25/30mph.. I wouldn't know since the Speedometer wasn't working and I also noted tran temp wasn't working so I guess this all points to TCM not communicating.

I foung this similar thread but he doesn't identify what fuse was causing the issue.

https://www.schoolbusfleet.com/forum...TOPIC_ID=18066