Speedometer under registers

[Jehu]

Tire size... checked that first thing. The tire size is exactly what's on the door tag.

I'm getting a 25% correction factor. That is, Speedo reads 40, I'm going 50 according to the GPS.

I haven't checked the odometer yet but I'm pretty sure that it's under-registering too.

On my old '75 Chevy, I had some trouble getting the right module to correct for larger tires. In those years, it was actually a gear reduction device that has male/female speedometer cable connections. It went right onto the tailshaft of the t-case. Is that the way they still work on the '93?

 

[skylark]

Nope. It is electronic. What year is the vehicle?

 

[Jehu]

1993 K1500 5.7L TBI, 5-Speed Manual

 

[someotherguy]

Easy... http://tbichips.com/?page_id=504 except ignore what the guy says about "the other dude did dip switches blah blah" I say screw moving the jumpers around; if the first combination you try isn't dead accurate you will want to change it and try others. Sometimes you can try 2 or 3 different settings before you get it just right. So, soldering in a dip switch is easy and super cheap. Your '93/manual probably has the DRAC with the single bank of jumpers, so a single dip switch is cake:

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"Saving money" by not installing a dip switch is totally laughable. They cost almost nothing.

Richard

 

[Justin S]

I recently bought a GPS Speedo from eBay. It was 40 bucks, and just displays the mpg in big green numbers, and it's accurate for whatever tires or gears you want to run

 

[sewlow]

http://appcrawlr.com/android/digihud-speedometer#authors-description

(More at the bottom of that page.) Lots are free. Free! Woo!

I broke the clip off of a belt holder. Some velcro.

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Power cord even worked!

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Flasher switch clearance.

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Crappy pix. Camera didn't know what to focus on.

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[Justin S]

Mine had the option for HUD but I just velcroed it to the gauges covering the Speedo. Mine simply plugged into a 12v power outlet so no hard-wiring needed.

 

[Jehu]

Thanks for the ideas. I have a habit of putting my phone in a holder by the rear view mirror. I use Waze all the time. The vehicle speed (GPS derived) is shown in the lower left corner. If the speed limit of the road I'm on is in their database, I also get little red marks showing that I'm over the speed limit. I'm okay for now but I would like to get the speedometer (and odometer) working properly.

 

[Justin S]

Its also possivle that someone swapped the ring and pinions for a different ratio. Since its that much slower, maybe they went from 3.73s to 3.42s or something.

 

[Jehu]

Its also possivle that someone swapped the ring and pinions for a different ratio. Since its that much slower, maybe they went from 3.73s to 3.42s or something.

That's a scary thought. I still haven't shifted into 4x4. I once bought a Jeep that someone had replaced the rear axle in. The ratios didn't match up so it would roll 5 feet and bind up.