We’ve got a 2019 Cat 908M that has random electrical loss which either shuts the machine down or creates a crank no start situation. Occasionally after you turn the key to the on position, and enter the password the machine will crank but not start. When this happens there is power to the dash behind the steering wheel and the overhead password panel. There is a red flashing exclamation point, the glow plus do not turn on and there are asterisks in the upper right corner of the display. There is no power to the switch panel to the right of the drivers seat. Sometimes keying the machine on and off fixes it. Sometimes if you leave the key on the red exclamation point in the dash goes away and you get power to the right side switch panel and it will start. Other times you give up and walk away and it will start later in the day. It will sometimes do this after sitting overnight and other times right after you’ve turned the machine off and try to restart. It’s completely random. Occasionally when the machine is running it shuts itself off. Same symptoms as above. Sometimes it will start right back up and other times it won’t. It used to do this once every few months. Then last week it started so it multiple times per day. It went to Cat about a year and a half ago and of course it worked fine so they couldn’t find anything wrong. Anyone have any ideas? Maybe ignition switch or a computer issue. Hopefully not a chafed wire somewhere. I can get the serial tomorrow when I’m back at work.
You'll need the S/No to get an electrical schemaitc. Also it's probably going to be necessary to find what Diagnostic Codes/Events are or have been present recently. That will give an idea where to look.
MHK5800700 When this first happened a year and a half ago I had a friend swing by who has ET. He said he didn’t see any current codes or events. I’ll give him a call in the morning and see if he can came by again to see what the computer has to say.
It's a good job you know someone with ET because it's the only way of accessing Diagnostic Codes/Events on that particular model. Please ask him to connect ET and to download a Product Status Report. Make sure he ticks the "All ECMs" check box to download info from every ECM on the machine (from memory I think there are 3) . Then either post the pdf file here or send it to me by PM - your choice. Also Please ask him NOT to erase any Logged Diagnostic Codes/Events that he may find just yet.
Thank you Nige I will report back. It may take a few days
That's fine. We won't be going anywhere.........
Well i got lucky. The problem turned from intermittent to permanent so it was easier to look for a fix. It ended up being the relay circled in the photo. Its not labeled in the fuse panel door or the manual for the machine. It took the parts guy at Cat a while to find it too. Interestingly its the only relay that doesnt have a Cat part number stamped on it. The parts guy said it was a "main relay". The machine has been in use for a week with no issues so far. Thanks for the help
Glad you got it sorted. Marked as "Main Relay A" (one of two identical relays, the other one being "B") on the schematic. BTW the large unit just to the right of the two relays in your photo is the flasher assembly.