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Welcome to the 3500HD.com forum created October 2009

Author Topic: speedometer off?  (Read 2058 times)

454-3500-hd

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  • Age: 30
  • Location: maryland
speedometer off?
« on: June 22, 2011, 07:05:04 PM »
My speedometer in my 91HD is off by about 10mph. 4l80e trans. Anyone have any ideas on how to fix this problem? Thanks

Eric
My fleet,
91-3500hd-454
Ms660-magnum stihl
Modded-288XP husqvarna
Modded-homelite super 2

ED-NY

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  • Location: Champlain, NY
Re: speedometer off?
« Reply #1 on: June 23, 2011, 07:37:53 AM »
Eric

Someotherguy must have made this tech tip, it outlines installing a DIP switch on the DRAC (digital ratio adapter controller).

I may have an extra DRAC if needed.

http://www.someotherplace.com/guides/clusterswap/cluster.html

This site concentrates on the DRAC itself and has the jumper combos:

http://www.tbichips.com/drac/


Ed
« Last Edit: June 23, 2011, 07:43:01 AM by ED-NY »

someotherguy

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Re: speedometer off?
« Reply #2 on: June 23, 2011, 12:03:32 PM »
Hey Ed,

That cluster swap article is actually an ooooollllld one that someone posted on FullsizeChevy; the picture links kept dying so I dug them all up and put them on my site just to preserve them - I don't take any credit for the pictures or info.  The article is actually for retrofitting a 1992-1994 cluster into a 1988-1991 model, to get rid of the "moonie" gauges.

Now the "moonie" gauges, 1988-1991 have the speed sensor buffer built into the cluster, instead of a separate DRAC module.  You can modify the moonies with a DIP switch much the same way you'd modify a DRAC, but the settings don't work the same way as detailed in that article or in the TBIChips info.

There's a different table of settings and unfortunately instead of being based off measurements and a formula, it's predetermined info based off axle ratios and tire sizes, and the 3500HD stuff isn't included in the particular examples I've found - presumably as the info was released prior to 1991.  Sooo, could be a little bit of trial-and-error to break this down to something that will work for a 1991 3500HD, the only year HD that would have a cluster with built-in speed sensor buffer.

Here's a link I wrote to the info on 1988-1991: http://www.fullsizechevy.com/forum/general-discussion/interior-tech/467576-recalibrating-1988-1991-speedometer-dash-cluster.html

Richard
06 Silverado ISS / 06 Silverado SS / 06 300C SRT8

454-3500-hd

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  • Posts: 89
  • Age: 30
  • Location: maryland
Re: speedometer off?
« Reply #3 on: June 23, 2011, 02:59:23 PM »
Thanks Richard and Ed

This seems to be out of my skill level. So I think ill leave it alone ;D. Last thing I want to do is mess up the electrical in my HD  >:(. I just put tags on the truck yesterday and she runs great, for being as heavy as it is, this big block puts your a** back in the seat! I can hear my e brake rubbing tho. Ill need to check that out. I had a dodge guy who hates the bowtie say its a good looking truck 8)! So that made my day.

Eric
My fleet,
91-3500hd-454
Ms660-magnum stihl
Modded-288XP husqvarna
Modded-homelite super 2

 


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