2nd Gen Non-Engine/Transmission How do I check the voltage at a fuse block?

[Crowhurst]

I'm trying to trouble-shoot failed dash illumination lights. I have the factory service manual at pages 8W-40-4 & 8E-18. Fuse 5 in the junction block by the steering wheel is good, and I now need to check the voltage at fuse 5 while rotating the dash light dimmer. I'm over from Great Britain, so please excuse my ignorance as to how to check this voltage on a USA truck. The thinnest probes from my multimeter do not reach inside the fuse block when I have removed the fuse. Is there some clever device that replaces the fuse, or a small flat probe to adapt the multimeter, or do I use a straightened paperclip?
Nick.

 

[B.G. Smith]

I'm thinking you are wanting to check the resistance in the circuit as you rotate the dimmer. I believe the circuit is 12v + to the fuse, through the fuse to the lights then to the dimmer swhitch which adds/removes resistance to ground to dim the lights. I haven't seen a thin blade probe that would go into the small fuse holes. A flattened paper clip might work. Welcom to the USA, hope you enjoy. bg

 

[Crowhurst]

Thanks, bg. The manual shows that 12v goes to the switch, and the voltage is then varied between 0 and 12 volts before it goes to fuse 5, which is why I need to check it.
Nick.

 

[Crowhurst]

I found the correct tool to probe the connectors on this truck. It's described in the Factory Service Manual at Page 8W-01-9 as Special Tool 6801. The tool is available at various places on-line, but I found the best deal was to buy the Miller 10190 Electronic Probe Kit. This contains two probes, and cost $18 including postage via Ebay. This tool was very effective in trouble-shooting several different connectors. The recess at the back end of the probe was too large for the probes on my DVM, so I used some leads with crocodile clips.
Nick.

 

[Road Dog]

You can use a "fuse tap", which is simply a metal tab, to expose the voltage connection. It's meant to add a circuit and is available at any auto supply store. Or use a paper clip. Pull the fuse and then slide in both together.
#ad