7710 charging system question

edhOH

Member
I have a 7710 force 2 tractor. The charging system light came on a while back and I finally got around to doing a little diagnostics. I measured 12.5 across the battery terminals with a fully charged battery. When running, I get the same reading at the back of the alternator. Would this reading cause the battery to not charge? I don't run the tractor all the time, maybe every couple weeks. I noticed after a few months the battery getting low and put it on a trickle charge.

I am trying to track down the issue and get the battery charging again with winter just around the corner. thanks.
 
A battery should read 12.5 give or take a bit with out the engine running but with the engine running and the charging system working you should get 13-14 volts give or take a bit. If you do not get that 13-14 volt when running the charging system si not working and time to have the alternator checked at an auto parts store or other such place that has equipment to check them
 
Series II tractors should have the Lucas/Magneti Marelli nightmare on it, which has an internal regulator.

What IS near the battery is a battery temp sensor. If this circuit is damaged/faulty, it will create a no-charge condition.
 
Bern,
Have you ever dealt with one of those tractors presenting an intermittent charging problem.... where the problem was in the printed circuit of the cluster?
I've repaired/replaced all of the wiring from the bulkheads (including) forward, gone to a 10si alt and eliminated all unnecessary wiring... and still I get an occasional charge light. So I'm basically down to suspecting either the pulleys are worn out or there is a fault in the cluster... Just curious if you've seen something like that.

Rod
 
The indicator lamp circuit is only used for initial excitation, so once the alternator is up and charging, it shouldn't need to rely on a functioning indicator lamp circuit.

Is it in fact not charging when the light is on? I doubt it could be a worn pulley unless you're running very high electrical loads.

As for printed circuit boards, I can't say as I've ever seen a faulty one on a Ford tractor. I've seen my share of malfunctioning electronic instrument clusters, but nothing related to the indicator lamp circuits. I'd suspect the bulb holder before the PC.
 
This one does have a couple extra lights so it's certainly got plenty of electrical load... I haven't verified yet if it's charging or not when it flashes the indicator. Sometimes it's just dim. It's really been so intermittent yet that I haven't stopped to diagnose it. Was really just wondering if you'd seen problems with the instruments before. Thanks.

Rod
 
Indicator light receives voltage from output of the switch and sees ground through the alternator so lamp is on. This signal jump starts the alternator when engine is started. When alternator starts charging the alternator end of the light sees 12 volts so lamp goes out. Without a functioning lamp the alternator will not begin to charge, but serves no function once alternator turns on and lamp goes out.

I have a 5610 Series II with Lucas alternator. It requires functioning lamp and a voltage signal through a temp sensor on the bottom of the battery tray. My 5610 had a no charge condition. Lamp came on but would not go out when engine started. I read no voltage at the battery sensor terminal on the alternator. Traced problem back to a broken wire in the battery sensor circuit. Repaired that and charge system works.
 

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