Volvo L70 Starter

[karlbradshaw]

Hi all

My old L70 (Volvo / Michigan) won't start. It was fine yesterday when I parked her up, but this morning, it wouldn't turn over.

Both batteries OK so I tried jumping from the power lead on the starter to the solenoid but still nothing. Assumed starter motor failed.

Took the starter off ready to send away for repair. Quickly bench tested it and the solenoid engaged and spun.
So fitted it back on, turned the key but nothing. The dash lights dim out when in crank postion but it's not cranking over.

So what's happening now is if I bridge the solenoid from the power lead it cranks and starts, so I've eliminated the starter motor. However once started and ignition on I have no gears. All dashboard works OK just no pwer to gear shuttle, it's as if you're trying to start it when in gear (ie not cranking over and the dash lights dim out).

So I can basically start it now (although not by the key) but I cannot move it. Assuming maybe power to the gear shuttle ecu or something? Any help would be greatly received.

Thanks everyone

Karl

 

[Delmer]

I'd start at the key switch. Does it have power? and does it turn on the power to the run and start terminals when you turn the key? after that you're going to need a wiring diagram.

 

[karlbradshaw]

Thanks Delmer. Yes it has power at the key switch, and power goes to the starting wire but it does not go to the solenoid so somewhere inbetweeen theres a problem. I'm not sure if these have another solenoid somewhere. I'll try and find a wiring diagram somewhere...

 

[Delmer]

Well then, I don't know how old, and even if I did, I wouldn't know the wiring diagram of a michigan, but typically there will be a neutral switch in the starting circuit. You can confirm it's operation easy enough, or hold the key to start and shift in and out of neutral a few times.

 

[funwithfuel]

Check ground cable, frame to flywheel housing. They have a tendency to break right at the lug. In response to your conversation with Delmer. There should be a crank relay with a crank inhibit relay. If memory serves me. I'll see if I can find schematics and parts doagram, but it's spotty with those old machines.

 

[funwithfuel]

Got s serial number?

 

[karlbradshaw]

Hi guys, thanks for your replies.

Manufacturer number 7324, serial 33111.

I tried starting it earlier to lift arms by shorting to solenoid but it wouldn’t go, it’s just clicking. It wasn’t doing that earlier. I’m going to bench test again tomorrow but might have to send starter away to have it checked. Still no 24v at starter ring terminal solenoid when key in crank, even though ignition barrel sending power out

 

[karlbradshaw]

 

[karlbradshaw]

Have gone through this and all relays seem ok. Hoping the ground cable is damaged, but that still wouldn’t explain the lack of voltage at the solenoid when cranking. I have found another solenoid on the left hand side near the engine but it has wiring to inlet manifold so I think it’s to do with cold start.

 

[funwithfuel]

First, How are the grounds?
Next, how is the master switch. When you close it, does it snap with authority or is it just like turning a rusty switch? Do you have a voltmeter and a helper? Voltage drops will tell you what you want to know and where to look.
There should be a fuse to the cab feed.

 

[karlbradshaw]

OK, so I've gone through all wiring, the battery terminals, master switch, ground to chasis and the chasis to engine (the ground is on the starter motor).
These all are OK. Starter motor is defiantely OK, I've bridged it out and got it running, but still have no power to gear shuttle so it does not move.

All fuses and relays OK. Am going through wiring diagrams now but just wondered if anyone else had any suggestions.

The gear shuttle lever is only a month old so I don't think it's that.

Cheers

 

[funwithfuel]

If you look at the ECU, There's a screw-in cap for a 2or3 amp fuse.

 

[funwithfuel]

Here's some guidance

 

[funwithfuel]

A little more

 

[funwithfuel]

Troubleshooting guidance
This is all I have. Prosis has purged the old service files. These are from the L70/90/120 book.

 

[karlbradshaw]

So it looks like the glass fuse has blown

 

[karlbradshaw]

As soon as I put a fuse in it pops, any ideas?

 

[karlbradshaw]

I'm lost. I've got an ignition live so my weigh loader works. I can directly wire the starter solenoid so I can start her. Does anyone know if I can put a direct live to the gearbox to get the gears working?

 

[karlbradshaw]

Many thanks FunWithDiesel.

I’ve swapped plugs on ECU and bypassed the R2 relay. Wired starter directly to ignition.

I will look at insulation on relay housing and see if that’s where the fault lies. But at least now it’s running.

 

[karlbradshaw]

Next job to brave fitting a front crank seal. Hopefully it’ll pop out and I won’t have to take the casing off.