speedometer not working - The 1947 - Present Chevrolet & GMC Truck Message Board Network

nrasac · 02-18-2014, 03:04 PM

I have a 81 c10 with a 72 350 engine. Has a th350 automatics transmission w-cruise control. Speedometer has not been for about 6 months. It stays steady below zero and once in a while it bounces when road is bumps. It has two speedometer cables.

Best way to diagnose. I read other posts on the subject but am still confused. When using a drill to check if speedometer turns, do I use the drill on the inlet that goes directly into transmission. I still have speedometer cable attached to truck so I do not how difficult it is to remove but looks easy.

Thanks , on my last matter I finally replaced temp gauge with mechanical and truck is running fine, the old gauge was off by 35 degrees. Thanks for the help.

nrasac · 02-18-2014, 04:36 PM

Truck has two speedometer cables. I was wondering what is the best way to check cable that attaches to back of gauge ( hoping I don't have to take off gauge cluster. Also, when putting my head near the brake, I found the speedometer cable, but could not see where it connected to gauge . I might take another look. If I decide to take gauge panel off, is there any tips to safely do it, and how much give will dash have so I don't pull any wires out. Current symptoms speedometer does not move only when driving under bumps and odometer does not work, odometer takes about a month to register a mile.

I am new at this and only with dash is taking it off to replace wiper switch.

mrolds88 · 02-18-2014, 05:19 PM

Easiest way is with a drill and a buddy. Disconnect the upper cable at the box on the fender. Hook up the drill to that. if that works, then get your buddy to crawl under the truck and disconnect at the transmission. Hook up drill again. I would think that the lower cable or the box would be my first suspects.

nrasac · 02-19-2014, 10:03 PM

I was checking how easy it was to remove cable end from the fender side, then I immediately retightened. When driving today it was working. Hopefully, it was just loose or the line was really finicky because it is working now. If it holds up that sure would be an easy fix.Thanks for help mrold88.

Justin

02-18-2014, 03:04 PM	#1
nrasac Registered User Join Date: Oct 2013 Location: Covina California Posts: 14	speedometer not working I have a 81 c10 with a 72 350 engine. Has a th350 automatics transmission w-cruise control. Speedometer has not been for about 6 months. It stays steady below zero and once in a while it bounces when road is bumps. It has two speedometer cables. Best way to diagnose. I read other posts on the subject but am still confused. When using a drill to check if speedometer turns, do I use the drill on the inlet that goes directly into transmission. I still have speedometer cable attached to truck so I do not how difficult it is to remove but looks easy. Thanks , on my last matter I finally replaced temp gauge with mechanical and truck is running fine, the old gauge was off by 35 degrees. Thanks for the help.

02-18-2014, 04:36 PM	#2
nrasac Registered User Join Date: Oct 2013 Location: Covina California Posts: 14	Re: speedometer not working Truck has two speedometer cables. I was wondering what is the best way to check cable that attaches to back of gauge ( hoping I don't have to take off gauge cluster. Also, when putting my head near the brake, I found the speedometer cable, but could not see where it connected to gauge . I might take another look. If I decide to take gauge panel off, is there any tips to safely do it, and how much give will dash have so I don't pull any wires out. Current symptoms speedometer does not move only when driving under bumps and odometer does not work, odometer takes about a month to register a mile. I am new at this and only with dash is taking it off to replace wiper switch.

02-18-2014, 05:19 PM	#3
mrolds88 Registered User Join Date: Jul 2011 Location: WV Posts: 946	Re: speedometer not working Easiest way is with a drill and a buddy. Disconnect the upper cable at the box on the fender. Hook up the drill to that. if that works, then get your buddy to crawl under the truck and disconnect at the transmission. Hook up drill again. I would think that the lower cable or the box would be my first suspects. __________________ 72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD

02-19-2014, 10:03 PM	#4
nrasac Registered User Join Date: Oct 2013 Location: Covina California Posts: 14	Re: speedometer not working I was checking how easy it was to remove cable end from the fender side, then I immediately retightened. When driving today it was working. Hopefully, it was just loose or the line was really finicky because it is working now. If it holds up that sure would be an easy fix.Thanks for help mrold88. Justin

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