Last try...

[BOOYAHGRANDMA]

^^ Once I hooked the battery back up the speedo and odometer never moved again. I have checked a number of the grounds but have not took them off and really cleaned them up well , I will check that today though. I have checked the harness by the fuel filter and it is all on the up and up . I ohmed the harness coing out of the cab and it reads 1.4ohm as does the pigtale that plugs into the diff sensor so I dont think there are any problems there , due to the fact I have the same ohm reading at both test points.

 

[BOOYAHGRANDMA]

Little update for any one trying to keep up with this whole non working speedo deal. Today I went over and made sure all the grounds are clean and in good shape tested them out with a test light hooked to the battery and they all checked out fine. Going to try and tear down the dash again and pin test the wires leading into the speedo and see where that leads too...

 

[Duane867]

I'd say your problem is behind the dash in the cluster its self, or the connections to the cluster.

 

[SMTGREG]

Have you pulled the codes for the GEM? If you have cruise control does it work properly? The GEM processes the speed signal from the speed sensor pins #9 and #18. Then outputs the processed signal from pin#1 to the inst cluster, speed control (if equipped) and the PCM. Test the resistance of the gray/black wire from the GEM pin 1 to the Inst cluster pin 1 It should be less than 5 ohms. If all tests ok the speedo has probably electrically failed.

 

[BOOYAHGRANDMA]

^^ Going to tear into it later today hopefully , the only code i am getting right now is the p0500 code , I will check the ohms here in a bit and let you know

 

[BOOYAHGRANDMA]

Alright went a head and tore it down again and tested the GEM pin one and the cluster pin one and get an ohm reading of .001 Now just to make sure I am not mixed up here I am testing the pigtale that plugs into the GEM and the pigtale that plugs into the speedo cluster , that ohm reading is .001 The reading was done with the truck not running and key in the off position...

 

[SMTGREG]

That is correct. Either the GEM or the speedo is not working properly. With proper test equiptment (IDS ) the dealer can pinpoint which one. I have seen more speedo's bad than GEM's.

 

[BOOYAHGRANDMA]

^^ Thanks for the help , do you know any way to bench test the speedo alone to see if it is working right ? Also if i did need to change the GEM does it have to be flashed by the dealer or anything or is it as simple as a plug and play?

 

[runningslow]

You could try swapping gauge clusters with one from a junkyard. I think I paid $15 for one when I wanted to swap in a new one so I could have the factory tach.

The only "bench test" I know of for the speedo is to pull the gauge and applying a AA battery to it, like detailed in the Tech Section here, about a 1/3 of the way down the page: http://www.therangerstation.com/Magazine/spring2009/odometer.htm

This may or may not help.

 

[BOOYAHGRANDMA]

^^Thanks man gonna give it a shot here in a few min.

 

[BOOYAHGRANDMA]

just too see what it would read as i hooked back up the GEM and tested the black/gray wire and the ground wire that plugs into the speedo and i get a reading of .927 ohms with the truck off and a slighty higher reading with the truck running , could this mean that power is going through the GEM to feed the speed and like mentioned before the cluster has just gone belly up? I still gotta check the speedo out will do that when i get home . dont have the tools here at work...

 

[BOOYAHGRANDMA]

Okay now its getting fun , I tested my speedo using the AA battery trick and it checked out fine , also had another cluster with a tach in it and it tested out fine as well both shot up to about 75-80 mph. Swaped out the GEM and pluged everything back up and still no speedo or odometer , rechecked the codes after driving aroung for a bit and still have the P0500 code. I am at a lost here , everything seems to check out fine but yet still no speedo or odometer , if any one else has any thoughts or ideas please pass them along....

 

[runningslow]

Have you tried both speedos in the truck? There may be another issue in the cluster itself.

The AA trick only really proves that the needle works as planned, but if you notice it doesn't make the odometer work. Its applying voltage differently than the GEM would. So, there may be something wrong in the circuits between the speedo needle and the harness.

I'm really out of ideas, though.

 

[BOOYAHGRANDMA]

^^ I have indeed tryed both speedos and still have the same end results. Swaping the GEM did nothing as all the results from the ohm readings stayed the same. I have power leading into the GEM and when I tested the black/gray wire from GEM pin ONE to Cluster pin one i get the .001 reading so i dont know??? Is there any way that the ABS module its self could be bad and be at the root of all this? I understand that they run hand and hand with each other ABS/SPEEDO so maybe that might be some thing to check...

 

[SMTGREG]

If your truck has ONLY rear ABS (RABS) the speed signal is processed with the GEM. If you have 4wheel ABS (4WABS) the speed signal is processed with the 4 wheel anti-lock brake module. Does your ABS work properly? Do you have speed control? Since you have replaced all the main components without results. Are you sure the parts you replaced are good? If they are then its back to the wiring. First check the fuses in the Inst panel fuse panel # 10 #20 and #25 for power with the key on. Another thing I have noticed that you checked the wiring for continuity. all the wires also need to be checked for short to ground. One lead on the wire and one on a good ground with the module disconnected it should be an open circuit. then test the same wires with a voltmeter with the key on for a short to power. I was just reading back the resistance of the speed sensor should be 800 ohms to 1300 ohms Not 1.4 ohms unless that was K ohms or thousands which would still be slightly high.