It starts and moves, but no gauges or display when key is turned, or started. I deoxed the big connectors going to the black box (no corrosion noted), checked for ground continuity at ground strap of black box, checked all fuses, checked the two relays inside that fuse box (starter and master, I think). I also checked the grounds in the instrument fold down access box (all good and clean). Key switch has expected output. I am scared to death it's that black box......please somebody tell me a work around. At the very least, I need to get alternator function back so that I can use it. I don't know if the black box was regulating the field current or not, or if it is a coincidental, unrelated failure. I remember seeing more than just the power wire going to the alternator, so it's likely not one of those self contained ones, right? History: I went to use it after pushing down a few small trees, but this time, no gauges. I checked to see if it would move (to take it back to the shed), and it did. It was hot out, and I didn't know there was no alternator, so I was using the A/C. On the way back, I found a few more to dig up, and it suddenly stopped moving. Now, I got out and walked all the way back home and got my meter. Batteries way down, and when I cranked it (enough power to crank that easy starting engine, even though it wouldn't move), there was no alternator charging. Ok, swapped good batteries, brought it back with no A/C or fan, and it made it. Then I performed the tests I listed above. It's hooked to a battery tender, so the batteries are capable of starting and moving it for testing purposes. I spent hundreds of dollars on a manual, which is very bulky and seemed complete. I went to the manual, and the electrical section tab was there, but the electrical pages have been taken out! Anybody have any links to the electrical schematics and connector locations and ID's.?
Here's a copy of the electrical schematic. I would probably start by checking power to the circuit breaker at location A6.
Thanks so much!!! Just to clarify, A6 would be referring to the grid (A vertical, 6 horizontal) of the schematic? If so, that 80a breaker is the only one I've seen, and it passes current and voltage. Is it possible that the dreaded black box controlled all the gauges and alternator? Is it normal to have alternator field current controlled by the same ecm box?
Hi, Assuming it is an original or similar the alternator is self exciting. If there is no output from the alternator it is faulty have you checked the out put? the monitor system is supplied by a fuse have you checked it? here is the electrical schematic
Cmark beat me to it
Yes, the fuse is good. When I saw it on the fuse box, I was really hoping it was the fuse. If the alternator is 'self exciting', does that mean it has an internal regulator? If so, what's the 3rd wire for? I've checked during the engine running and there's no voltage output. I didn't bother putting a current tester on it since there was no charging happening. With so many things going out, I looked out for damage from a tree branch or something, or a squirrel chewing wires, but can't see anything. It looks nice and clean, and all connections look surprisingly corrosion free (kept in a shed).
The alternator (if original) is self exciting and self regulating. All it needs is a ground and a battery + connection. The third wire is (someone correct me if I'm wrong) an AC tap to tell the monitor if the alternator is charging or not. Testing is simple. Check for battery voltage at the B+ terminal with your DMM. Check for current at the B+ terminal using a headlamp bulb or similar high amp load. Run the engine and see if the voltage rises. It's possible for the alternator to lose its residual magnetism and need re-exciting but your sudden failure mode pretty much rules that out. Can you clarify which Black Box you're referring to?
The black box is the sealed ECM or EHC (on the schematic, I think), which has 2 gigantic multipin connectors held in place by a 4mm hex socket screw each. The connectors stick out of the box at a 90deg angle. The connectors and the general layout looks like this, but without those 2 round vents I checked the alternator for output with a VOM on the batts after starting, no voltage rise, as you would normally get. It's just baffling how this all happened at once. I'm assuming that I would have seen evidence of the alternator not working the day before when all the gauges were working, but did not do any tests....however, I was using the A/C and it did not stop working, plus I was using the high fan setting, which sounds like a 2hp turbine with lots of air movement. IF the 'black box' (and it is literally black) is the EHC on the schematic, then it would seem to be correlating the track speed sensors and solenoids....well, those functions seem to work normally.
If the machine still drives then don't worry about the ECM. You need to be checking voltage at the alternator, not at the batteries.
OK, will do that, and I'll get the current meter set up, also. Thanks again for your help.
just to add to my comment " If there is no output from the alternator it is faulty" if the wire going to the R terminal (green wire)is grounded this will also cause no output from the alternator so when you check your output with the meter. Test with the wire connected and then disconnected
Thanks for that little tidbit! I tested today with that wire in place, and that could be the common thread linking the instrument monitor and the alternator failure. Since I tested, I saw on the schematic that it is a data wire of some sort going to the monitor. Will revisit this!
Green wire off, no alternator output, so ordered a replacement. Tried to get codes, but the round data plug is slightly deformed, so going to make some pin extension wires to check the codes. Spent a good while looking for obvious wire damage since I was pushing trees around, and branches can always find a small opening and cause damage.
While looking online for pinout of Cat diagnostic plug, I see that it EXACTLY the same physical layout of the pins, but missing a key on the center (ground) and very slightly different sizes of bore for the pins. Oh yeah,......it's wired DIFFERENTLY than the J1939 which is looks so much like. My diagnostic reader is capable of reading longer messages, but now I have to order an adapter or be very sure I'm jumping to the correct pins.
Your machine used a proprietary system called CDL (Cat Data Link) which, as far as I know, can't be read by a J1939 scan tool.
ohhh. Well, I already ordered an adapter, which is made for converting to J1939, but, like you said, it remains to be seen whether my reader can decipher it. Thanks again for helping me and all these folks with your experience.
Oh that's interesting. Do you have a link for where you purchased the adapter?
Yes: https://obd2allinone.com/products/catj1939.asp
Today's question: I have good power and ground at pins 1 and 2 of the multipin connector going to the monitor. There are a cluster of gauges on the left side of the dash panel, and they also show no signs of life when cycling the key switch 'on'; such as the gauges swinging full range then settling on a value. Do those also get 'driven' by the monitor electronics, or are they essentially stand-alone gauges as we would find on an old car? I've checked the grounds in that compartment and it looks clean and corrosion free, as well.
The "quad gauge" is driven by the CMS (Cat Monitoring System). If the CMS powers up OK then the quad gauge should self-test as well. As mentioned earlier, when checking for power and ground, don't rely on a multimeter, use a high-resistance test light of some sort. That adapter isn't going to help you. It's made for connecting a Cat comm adapter to the diagnostic port in an on-road truck.