I have an L48 backhoe that has intermittent starting problems. We are always able to start it with a heavy copper wire jumping the starter. Recently it started periodically turning over with the key, but the fuel solenoid did not have power so it would not start. After cranking a bit, it would suddenly have power at the fuel solenoid and the solenoid would activate, but then the starter would not turn over. We have noticed that when the solenoid has power, the starter does not have power from the key....when the fuel solenoid does not have power, the starter will crank from the key....Could this be caused by a bad relay? If so, can someone tell me which relay to check? What else should I check to fix this problem? Thanks in advance for any help in diagnosing this problem!
L48 Starter circuit issue.
- Thread starter mkserges
- Start date
It probably has OPC (Operator presence control), a box of tricks with inputs and outputs, to control starting and running regarding safety. If it won't CRANK, but starts when you jumper the starter motor, it could be a key switch, a starter relay, or an input to the OPC or the OPC. Inputs will be seat switch, neutral switch, clutch switch, PTO switch etc. If one of those switches is not in the correct position, it won't allow you to crank. If you have pto selected while operating and lift the seat it should drop the fuel solenoid, and cut the engine. Check the switches for correct adjustment/alignment. A wiring diagram from the WSM would be handy. The seat switch probably also has 2 positions for drive and backhoe operation, check your operators manual for use of the seat switch, flipping the seat up etc. if so required. Check the connectors on each switch, including key, start relay, OPC controller, fuel relay etc.
Thanks for the reply!! I checked the wiring connections and the switches. They seem to be working OK. The engine will now start and run for a while, then the fuel Solenoid will lose power and the engine shuts off. It will do this randomly whether the tractor is being used or just idling. When it stops there is no longer power to the fuel solenoid. The starter will crank, but will not start immediately after it stops. After sitting for a while it will fire right up. I checked for power to the solenoid and it is losing power when the engine shuts off. After sitting for a bit power will return to the solenoid connector. Could this be a relay that is going bad? Which relay operates the fuel solenoid?
Thanks, Mike
Thanks, Mike
Still looking for help with this problem. I think it is electrical but need help in determining which relay might be causing the problem. I have checked the fuel solenoid and it functions properly. If I remove the solenoid the tractor will run all day but I have to shut it off manually. I tried removing the relays one at a time to see which one was sending current to the fuel solenoid. When I pull the glow plug solenoid (160 on the messick diagram) it cuts power to the solenoid. This is listed as the glow plug relay. Can someone confirm if this relay is generally part of the fuel solenoid circuit? The circuit seems to fail after running for a while so i am not sure how to test the relay. Looking for suggestions on where else to look or how to test the relays. Thanks!!
North Idaho Wolfman
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I think 100 td nailed it when he said the OPC is failing.
The OPC controls the stop solenoid and the starter and just about anything else.
When they go bad, they do all sorts of sporadic things.
The OPC controls the stop solenoid and the starter and just about anything else.
When they go bad, they do all sorts of sporadic things.
And I'm sure NIW has been mucked around enough by intermittent faults caused by them!
Whilst the OPC could be the main cause, I would purchase (or scour the net) for a WSM, (workshop manual) with wiring diagram, it will help with this, as well as many things in the future I would expect. Normally the glow relay will be totally separate from the fuel shut off solenoid relay, so have a look for another. Getting the circuit diagram would help with fault finding and testing, as you may throw a relay at it, then an OPC, and eventually find there's a loose spade terminal or bad connector somewhere? Do the usual battery terminal and ground/starter terminal checks.
This thread throws some light on a bad OPC, may be worth a read.
http://www.orangetractortalks.com/forums/showthread.php?t=20835
http://www.orangetractortalks.com/forums/showthread.php?t=20835
There are 2 switches in the seat. One for operator presence and a seat swing switch. The seat swing switch has a long arm and shuts off part of the system. They have a habit of becoming maladjusted.
Any more pages or full schematic or redo scan?
My quick look, and I could be wrong, says power to the hold in coil of the fuel solenoid is there whenever the key is ON, and the pull in coil is powered when key START is selected.
The HST, PTO, Gear range and clutch switch are in the starter motor relay circuit, so AFAICS, there is no safety inputs in the fuel solenoid circuit. Maybe I'm reading/seeing the diagram incorrectly, I'll blame that on the scan!
Then again, this diagram shows the START circuit, so it may not show the full fuel circuit. So it will help him with the CRANK function, but maybe not with the RUN function.
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Thanks for all the feedback....weather turned cold again so I am waiting for a little warmer day to continue troubleshooting. Thanks for the wiring diagram!! The under seat safety switch has been bypassed so I'll check the one that activates when the seat is turned....If you have any suggestions on how to check or bypass the various safety switches until I can isolate the problem, that would be great. I am certain it is losing power to the fuel shutoff solenoid and that is causing the problem....I started pulling relays last week and found that when I pulled the one glow plug relay (according the Messick's diagram) it would cut the power to the solenoid. None of the other relays impacted it.....guess next I will try unplugging the control switches!!
Thanks again!!!
Thanks again!!!