neighbor has a old 988A sn 87A9964 which surprisingly good shape and tight he got it from a coal company and the only person who ever ran it was the owner. Now for the bad part it has sit quite a while and having problem with the wiring it will not charge and the heater for the engine doesn't work. The wiring is all still in the tubing that I can see it has 24V to the alternator until you hook the wire to the alternator which tell me it has a bad wire or connection some place has the Delco one wire alt. but there are two wires going to the big post and the back into the loom not directly to the starter anyone have a wiring diagram for this old girl or a idea where to start looking? Could just run a new wire directly to the starter but would like to fix it right if possible.
Look in the parts book it actually shows how everything is wired up. your working on a 988 87A. Bob
A delco one wire alternator only needs a connection to the battery +, that will be the big wire on a big threaded terminal on the alternator. That wire obviously should show 24V to ground all the time, ignition switch on or off. And 28V any time it's running. You shouldn't need any of the rest of the wiring diagram unless that main charge wire runs through an ammeter or a resistor for an ammeter.
Understand that the problem is there is no big wire only two smaller ones about 10ga or so and they don't go right o the starter but up through the loom someplace.
Thanks on of the guys at work can get into the SIS or what ever from Cat i will look monday
"Thanks one of the guys at work can get into the SIS or what ever from Cat i will look Monday" Not sure they will find much on SIS for that old of a machine, I looked quick and found very little! Attached fined the wiring diagram for the 87A6832 and 87A6868 and up machines. Apologize for the minor edits done back in 1988!
Had some problems with that last post I think I got it right now, hope it helps.
There is a Wiring Diagram on SIS for machines S/No 87A8207-Up which will be later than the one KSH posted above. His one is now titled 87A6868-8206. I don't know what differences if any there might be. I tried everything I could think off to print a copy to pdf but failed.
Thank you very much that gives me a place to start at least didn't want to open it up any more than necessary.
The two wires are used to allow the ammeter to reflect the charging or discharging of the battery only, without showing the total current used by the machine, you only care that the battery is being charged with an ammeter, just the way the gauge works. A 10 gauge wire is big enough for those days. Note the one o wire that goes to the ammeter and then to the manual circuit breaker. Kshansen may have a good idea where that circuit breaker is located? If the circuit breaker or connections are not making a good connection, then the rest of the machine electronics won't work. Also note the O wire from the alternator to the ammeter connects in the same place as the heat start switch, which would carry a lot of amps and be a likely place to have overheated connections. Does that switch work to engage the starter? but not the glow plugs?
Finally I managed to come up with this..........
Get the parts book it actually shows the components and the wiring looms and where everything is located. Bob