Power Shuttle failure - code 78? What's that?

[mahlers]

Re: Power Shuttle failure - code 78? What\'s that?

Hi Rick,

Thanks very much! I have a feeling that connector is unused because I can't find anywhere for it to plug into. It's got two wires - a solid black one and a brown/green striped one. I wish I had the wiring diagram!

It's a very bizarre failure because everything works fine and then, bam, it is totally disabled. I can shut the tractor down, restart, and everything is fine for a little longer. Then, bam, it disables again.

Thanks again for your help!

 

[RickB]

Re: Power Shuttle failure - code 78? What\'s that?

I verified that 78 does indicate an ECM failure. Of the three I have seen , I was able to download software in one and make it work, but only for one day. The second did not respond to a fresh download. The third one I encountered got a new ECU module without attempting a download. Yours probably won't reset itself too many more times. The troubleshooting flow chart for this fault is short and sweet; check continuity at an unused pin at the ECU's connector and toss the ECU if that pin is shorted to ground.FWIW, a recent change in the part number for the ECU was accompanied by a DROP in price from around $600 to about $300.

 

[RickB]

Re: Power Shuttle failure - code 78? What\'s that?

I pull for Chevies, specifically the 29 and 48 cars. But I appreciate outstanding talent in the driver's seat and on the pit box. Kahne, MacMurray, Jimmy Fennig were very impressive this weekend.

 

[mahlers]

Re: Power Shuttle failure - code 78? What\'s that?

Thanks Rick! I owe you one!!

 

[mahlers]

Re: Power Shuttle failure - code 78? What\'s that?

Hey Rick, do you know if this failure could have anything to do with the clutch switch? I was going through the wiring from stem to stern, and I found that the people who assembled this tractor didn't put a scuff protector on the wires going to the clutch pedal - and the wires leading to the clutch switch were scuffed down to metal and shorting to ground. I sealed it up, and ran the tractor for about an hour, and no faults showed up. I'm hoping that this might have fixed the problem. I'm going to run it like crazy tomorrow to see if it triggers a fault again, but from what I saw tonight, it seems to be holding together.

In a way I'm kind of hoping this wasn't the problem because I stripped the tractor down to the bare unit in anticipation of putting it on a roll-back and sending to the dealer. I don't look forward to putting the loader and backhoe back on if I didn't need to take them off...

Thanks again!

 

[RickB]

Re: Power Shuttle failure - code 78? What\'s that?

I can't say for sure, but it certainly is possible. Would be interesting to pull the stored codes to see if any led to a short in the clutch switch circuit.

 

[mahlers]

Re: Power Shuttle failure - code 78? What\'s that?

Woohoo! I think the problem was a short in the clutch circuit. I just got done doing about four hours of work with the tractor, and no failure codes anymore. I never would have guessed that the clutch circuit could have caused that failure code - it was just dumb luck that I found the short. Now, gonna keep my fingers crossed that this was the problem and nothing else goes wrong...

 

[RickB]

Re: Power Shuttle failure - code 78? What\'s that?

My turn to learn from you, many thanks. I will file that info away; may help somewhere along the line. There is more to Code 78 than NH is telling us.

 

[mahlers]

Re: Power Shuttle failure - code 78? What\'s that?

/forums/images/graemlins/cool.gif Here's an update to that Code 78 PS failure - it definitely looks like it was the clutch switch circuit. After stumbling across that short, and fixing it, I've put about 20 hours on the tractor without any problems at all. I've even gotten confident enough to work it in deep water, mud, and muck - which says a lot because if that tranny disabled on me when I'm shoveling muck out of my creek, I'd be in a world of hurt.