I’m having an issue with my speedometer calibration that I can’t figure out, hoping someone here can shine some light on the problem.

Here’s the deal:

When I go through the steps I get the first message on the odometer screen saying “E 08 6” which tells me that I have 6 tries left at recalibration. So far so good. Then when I hit reset I see “CAL972”. Here comes the issue, when I hit the select button to toggle to a different value nothing happens. Everything I’ve read says that every time you hit select at this stage it should let you cycle through the numbers but nothing happens when I hit the switch. I’m stumped. The select switch works in its normal function every day as I use it to toggle the tripmeter to calculate my real world mileage. I also have the PSOM grounded via alligator clips so I’m not sure why this is happening.

Any ideas?

Thanks in advance

 

Is this Speedometer/PSOM still in the truck?
If so:

Reprogram speed conversion constant using the following procedure:

-- Locate the dealer mode programming enable single-terminal connector. The connector is located at the bottom of the instrument panel below the center of the glove box. On all vehicles, the dealer mode enable wire is Circuit #567 (LB/Y).

-- Insert metal clip in service wire panel connector. Clip other end to vehicle ground while the key is in the OFF position.

-- Turn key to RUN (not crank) position while holding down the trip odometer RESET button on speedometer. Release RESET button.

-- Speedometer will prove out (sweep across dial and back). The English/Metric and revision levels will be displayed. The last number of the display is the dealer mode programming lockout count. This count shows the number of allowable conversion constant changes remaining. When the count is zero (0), no additional changes can be made to this instrument cluster. If a conversion constant change is required, a service instrument cluster must be ordered. Refer to this section for ordering information.

-- Press and release RESET button again and PSOM conversion constant (without the decimal point) followed by the word CAL.

-- Press and release the odometer SELECT button as many times as necessary to change conversion constant to the correct value.

NOTE:
Pressing and releasing the RESET button to lock in the new Conversion Constant reduces the number of times the PSOM can be reprogrammed by one count. The module can only be reprogrammed six times. If you change your mind and want to go back to the old conversion constant, turn the ignition switch off before you lock in the new constant.

-- When the correct new value is displayed in odometer window, press and release the RESET button to lock in the new conversion constant.

-- Turn the key off and remove the ground wire. Verify proper speedometer operation.

 

Right, so like I wrote I’ve followed the procedure exactly, but the issue is when I press the Select button it does nothing, won’t cycle through the numbers to allow me to change it. That’s why I’m stumped. I’ve never had this happen before.

 

Verify your jumper is good. Use a DVM to verify it is a very low resistance. If that is good, verify your ground reference is truly at ground.

 

Ok I’ll check those two and post back. Thanks

 

The volt meter says resistance is fine. Ground verified as good as well. Here's the real kicker though, I tried the procedure without anything plugged to the PSOM and it still gave me the "E 08 6" screen, then the 972CAL screen, but will not let me change values with SELECT. Is it supposed to show that with nothing plugged to the PSOM??

I'm truly stumped here guys.

 

Yes it does display the same info without the service lead grounded.So now you need to ohm out the LightBlue/Yellow wire back to the PSOM. If the test lead is good. You have a good ground the last part of the puzzle is the path back to the PSOM.

 

I'll test out the path back to the PSOM and see what I get. Is there a fuse tied into this system that I should be checking as well?

Thanks again for all the help.

 

Not for the test lead that I am aware of.

 

I know you say you've checked ground, but when I first attempted mine, I had the same issue--I couldn't get it to go into calibration mode. I had my ground connected to a bolt under the dash, which was apparently not sufficient. So I instead connected it to the ground of my cig lighter and it worked perfectly.

 

Ok I’ll check that out. I’ve been grounding it to a metal bracket that bolts the dash to the firewall. I’ll double check the ground. Thanks