Fan Speed and Speedometer issues

[Raymond Thompson]

I've got two unsolved problems to which I can't seem to find the answer .......1. My 72 air conditioned C-10 truck has a 3 speed fan switch however, it only runs on low and medium. When I switch to high it slows to almost nothing. I've replaced the switch - same result. What am I missing here???


2. I can't get the speedometer to work. I have replaced the TH350 transmission with an TH200-4R and I have installed a new cable. I can feel the cable turning as I roll down the road, but the speedometer doesn't work when I hook it up. I can spin the back of the speedometer and the hand moves and seems to work fine. Again - what am I missing??? I would appreciate some advice...

Raymond

[Longhorn Man]

#1, you need to check the relay, and make sure it is mounted tight to metal so it grounds.
#2 Make 100% sure the cable is plugging into the speedo head and not just sitting up against it. Sounds stupid, but it is an easy mistake.

[maddog1331]

Originally Posted by Longhorn Man

#1, you need to check the relay, and make sure it is mounted tight to metal so it grounds.
#2 Make 100% sure the cable is plugging into the speedo head and not just sitting up against it. Sounds stupid, but it is an easy mistake.

X2 on number 2.....I have made this mistake a few times. You have to make sure that the cable is really sitting in there, as you can screw on the cable without it actually seating into it.

[Raymond Thompson]

What relay are we talking about? The one on the right hand side of the firewall next to the vent?

[Longhorn Man]

should be mounted on the heater box, inside, on the passenger side towards the kick panel. (i think we are both talking about the same area)