Cruise Control and the speedometer

[possum70]

1978 Blazer. I found out the speedometer doesn't work. The cable is hooked up to the TC and to back of speedometer. Then I noticed there is a cruise control module bolted on driver's side wheel well but it doesn't work. I went looking for the fuse but couldn't find where it is. if the fuse is blown for cruise control will it keep the speedo from working? I'm thinking I'm just gonna remove the CC. Thanks for your help,

possum

 

[84 k5 blazer]

The speedometer is cable driven (mechanical) which would need only power to light the cluster for you to see it. I would start by checking your cable to see if it broke, then on to the gear that can be removed from the Transfer case.

 

[dremu]

As mentioned the speedo is mechanically driven. There are two cables, one from the transfer case to the cruise module and one from the module to the speedo. If either gets dry they will start to bind and then break internally.

If it were me, I'd undo the cable at the cruise module and see if it'll stretch to the dash cluster -- if it's an aftermarket cruise it's likely they didn't replace the cable with a shorter one. If it does fit, now is a good time to lube the end of the cable with a medium lithium grease -- IIRC there is something purpose-made as well.

If it doesn't fit (i.e. if it's factory cruise) you could just get a new cable at the parts house, install, and be done. The 70's factory cruise controls are hard to find parts for, and the only ones I've seen have all had worn out bellows

-- A

 

[Blue85]

As mentioned the speedo is mechanically driven. There are two cables, one from the transfer case to the cruise module and one from the module to the speedo.

I have never seen this setup. What years did it run? I have only seen the ones with the optical pickup in the speedometer for the cruise control. I know I have seen that from at least '82-'89.

 

[clandr1]

When my speedo wasn't working, it turned out that the male end of the speedo cable had snapped off in the back of the gauge cluster. Just had to go to NAPA and a new cable was only around $20.

Autozone's website shows they have several different lengths of speedo cable for your truck. I'd replace both the trans-cruise module cable as well as the cruise module-speedo cable.

http://www.autozone.com/autozone/pa...filterByKeyWord=speedometer&fromString=search

 

[dremu]

I have never seen this setup. What years did it run? I have only seen the ones with the optical pickup in the speedometer for the cruise control. I know I have seen that from at least '82-'89.

Oh, pre-'81 ... I had a '77 with it, for instance.

-- A

 

[British Slave]

I had an 82 that had that setup.

 

[AZ79K5Project]

My 79 has it. All mechanical cables. More than likely, as everyone said, one of the cables is broken or the gear is broken.

 

[possum70]

Well, I'm guessing it had broken in one of the cables. I could turn the bottom hole of the cruise module and the top would turn. I replaced it anyway with just one cable. So no more cruise. I just unhooked all the hoses to it. Are any of the hoses needing to be hooked elsewhere? I'm guessing vacuum hoses. The vacuum stuff is a bit over my head still.

possum

 

[84 k5 blazer]

My truck had all the cruise stuff ripped out before I got it, They ended up taking all the vacuum lines out that went to the charcoal canister and the 700r4 lock up. I wish that they did not unhook anything. If I was you I would leave it and get it fixed.

 

[British Slave]

Well, I'm guessing it had broken in one of the cables. I could turn the bottom hole of the cruise module and the top would turn. I replaced it anyway with just one cable. So no more cruise. I just unhooked all the hoses to it. Are any of the hoses needing to be hooked elsewhere? I'm guessing vacuum hoses. The vacuum stuff is a bit over my head still.

possum

Be sure and plug the hoses you disconnect.