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Fuse 21 is supposed to be a 15 amp, please confirm it is 15 amp in your truck.
Fuse 21 feeds the instrument cluster via connector C220B (18 pin connector). Trouble shoot by disconnecting C220B at the instrument cluster, replace fuse, turn key on, did it blow? If so you have a chafed wire, likely rodent damage, which you need to chase down. The wire is Black/Light Green. If it did not blow the problem may be in the instrument cluster. Visually inspect the instrument printed circuit board for burn spots ands see what you find.

BTW- problem could be in Fuse Box (Central Junction Box) but unlikely. Is fuse box burned or damaged at fuse 21?

 

Thanks, I will do that.

 

Thanks, I will do that,

 

Thanks, I will do that.

 

Hi,
Yes, fuse 21 is a 15A. The fuse box looks fine, did not see anything off.

Appreciate the advice, I will give it a go as soon as I have time!

 

Hi Jimboy,
I unplugged Connector 220B as advised and turn turned the dimmer up, and Fuse 21 did not blow. Does this mean it is the instrument cluster causing the short?

Thanks

 

Forgot to mention that I did visually inspect the instrument cluster after removing it and there are no visible signs that something is wrong.

 

I was hoping the problem would be found by disconnecting connector C220B. The Black/Light Green wire feeds 12v to the cluster. If it did not blow the problem may be in the instrument cluster. I have no internal wiring diagrams for instrument clusters. You may want to send your cluster to a rebuilder and have them test it or just replace which requires programing, I believe.

 

Hi,
So, I tried replacing the instrument cluster and the dimmer switch but neither resolved the issue. I am thinking of either trying to replace the Instrument Cluster Connector (C220B), or somehow installing a new wire somewhere, although I do not know if that is a feasible option.

Thoughts?

Also, do you know what wire feeds the dimmer switch? Does the same wire feed anything else?

Thanks