champion 736a with Volvo powershift motor grader wont move. Brake failure light flashes intermittently and relay clicking in armrest (fuse panel area). Swapped relay with another known good relay and same issue. Machine started having issues with defaulting to neutral when using. If machine was shut off and left alone for 10-15 minutes machine would drive again. Tested alternator, system voltage in operating range. Checked all machine grounds. Transmission Solenoid resistance values 28-29 ohms spec is 28.8 +- 5%. Volvo dealer not interested in working on or getting back with information.
Some things to check: Have you verified park brake is actually releasing? Hydraulic pressure low? Just guessing here based off recent work on a 740A. I think park brake is on the driveshaft. Fail light is probably powered by voltage coming through a pressure switch in the brake circuit. That may also declutch the tranny. Just tossing out an idea. Do you see the driveshaft rotate a little when put in gear? Are you actually getting 12V to the fwd clutch solenoid when put in fwd? Those graders used multiple different transmissions so getting that info on here might help.
You may want to check the wires coming out of your shift lever. Remove your console cover , it's a little tricky. Underneath your lever you should see a bundle of wires bonded to the bottom, not serviceable at all. Those wires tend to break from up and downshifts. It was a poor design, not improved on to my knowledge. I recall chasing brake switches and other things to find broken wires. Volvo won't help since they gave up on graders. Sold it off to someone else iirc. Post your serial number, it may allow us to offer more help.
It’s been a lot of years since I had anything to do with anything that far back. Does the electric back up motor come on if you step on the brakes with the engine off? There’ll be a couple of pressure switches for that. I’m not sure if any would be tied to the transmission controller circuits. That is an old square back and not from the changeover when they were renamed Volvo, am I correct?
Is it a joystick style controller or the older two stick style ?
Do you have the S\N of the machine and what is the error code
Guys, we're a month late to the party, I don't think he's coming back. No activity since his first and only post.