Superlift TruSpeed Speedometer Correction

 

The tire change from stock to 255/85 R16, combined with the gear chang from 4.10s to 4.88s, caused the speedometer to be

off by a lot. It was registering about 9 to 10 mph fast according to my GPS. I wanted to fix this for a couple reasons.

First, my odometer was reading more miles than actual and with my Toyota extended warranty coming to an end soon

at 100k, I wanted to have all the miles owed to me. Secondly, the Superlift website argues that performance

would improve with the computer getting accurate data. I am skeptical about this claim though. Lastly, I just wanted

it to read right.

 

I looked at three different options for correcting the speedometer issue.

They were: The Dakota Digital Universal Speedometer Signal Interface which retails for 80 bucks. Looks like it is not adjustable.

The Yellow Box from Black Robotics which retails for 100 bucks. Website claims it is adjustable. And the TruSpeed Sensor from Superlift

which retails for over 200 bucks and is also adjustable. I ended up going with the TruSpeed because it looked like it was the

easiest to install and calibrate of the three. It was also on sale for 189.00.

 

A friend and I installed the TruSpeed in about 4 hours. The install was pretty easy once we read the directions a few times.

The unit has four wires. A red positive, a black ground, and a yellow and green wire. The yellow and green wires splice into

the speedometer input signal wire coming off the transfer case.

 

There are three wires coming off the transfer case and the wire we needed was green with a red stripe. We traced the wire up the loom

and decided to splice into the wire where the loom is closest to the driver's side wheel well. Once the green/red wire was isolated

from the loom, the wires from the TruSpeed were spliced in. The green wire from the TruSpeed connects to the wire end

leading to the speed sensor on the transfer case. The yellow wire from the TruSpeed sensor connects to the wire end leading to

the computer.

 

We fabricated an aluminum plate that we could attach to the firewall in the engine compartment and we could attach the

TruSpeed sensor to that plate. The calibration was pretty easy and after a few changes I verified with my GPS that

my speedometer and odometer were back to reading correctly. The adjustment screws were weather proofed at the end.

 

Here are a few pictures of the install. This is the mounting location for the unit.

 

This is where we spliced into the wire loom.

 

UPDATE******** July 2008

Last month the unit started malfunctioning. The effects on the truck very very bad because it caused the truck to simply go to idle

speed and stop running all together. During this time the speedopmeter would swing wildly from side to side. Once I figured it out

and pulled the fuse I was back running. Until I got a replacement I ran in the stock configuration.

 

On July 11th 2008 I installed a new unit that Superlift sent for free. This time I ran it inside the truck just in case that was why the old one stopped.

Couple photos of the new (current) location. This photo shows the new access point I drilled in the firewall behind the passenger carpet.

 

Here is where the unit ended up, in the passenger floorboard tucked up high.