Need electrical help on a cat 320BL excavator - Inline fuse to ignition?

[BrianGrenier]

Need electrical help on a cat excavator. Someone who isn't me hooked up 24 volts reverse polarity to the drained batteries after the ignition switch was left on for a couple of days.. When the batteries were charged with negative polarity and the negative ground switch was flipped on, The circuit breaker blew.

Batteries were then drained 100% and charged up with correct polarity.

Now there is no electricity to the ignition switch. There is 24v electricity to the fuse box. Not all fuses, just about half are hot in the cab. Fuses like for the horn are hot. Circuit breaker checks good.

I did replace one switch all ready that is the new item in the attached picture. The picture is just the junction box ner the batteries in this Cat 320BL. I maybe will sell item #165-4026 (switch) on ebay; I paid $214.

There must be an inline fuse that I am not aware of. I am looking for it between the ignition switch and the junction box near the batteries. Any ideas where I might look for an additional Fuse that could be causing no power to the ignition? The top left item in the picture said slow blo on it...

 

[Nige]

Would an Electrical Schematic for the machine help your diagnosis..? If so send me a PM with your full machine Serial Number and your email address.

 

[lantraxco]

For sure take Nige up on his offer if you don't alreay have a schematic, they're priceless on this sort of problem.

There are probably several diodes in the system that will be toast if they had power to them, and there may be some electronic devices dead.

As I recall, one side of the fuse panel is controlled by a power relay (probably the one you have replaced), which comes on when you turn the key switch. Until you get power back to the switch I wouldn't worry about any other issues.

 

[BrianGrenier]

Thank you very much, Nigel for sending the scematic. I will need to zoom in to the pdf and take a good look at the schematic.
All the best,
B

 

[BrianGrenier]

My kid and I printed the pages out as a poster; 32 sheets, 4 across and 4 high and two pages.

 

[lantraxco]

Sounds good to me, those CAT schematics are hard enough to follow through all the connectors!

 

[BrianGrenier]

My kid wrote on the schematic: DFTBA..."What does that mean?". "Don't forget to be awesome!"

So, Good news! the schematic took me to the main fuse block and the ignition switch, 10amp fuse was blown. Easy with the right tools.

So, thank you Nigel, you are awesome! You gave me the tool to find the problem.