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Having one heck of a time recalibrating my speedometer. Help!


tsayyote

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Swapped axles in my '02 2.3L duratech 5spd from the 7.5" 4.10 gears to the 8.8" with 3.73 gears. My speedometer is off. When it says I'm doing 45mph, my gps reads 49mph and the gap gets bigger as speed increases.

I took it to ford and asked them to reprogram the truck for 3.73, which they did and charged $60. Drove home and the speedometer was still off the same amount. Took the truck back to them and they played with the tire sizes and went as low as they said they could and gave it back to me. Still no change in the speedometer.

I purchased Jet's Accu-speed module (I know a lot of you don't like Jet, but I got it at a good price, new). Followed the directions and hooked up the wires to they Gry/Blk wire (pin 14) that runs to the connector on the GEM behind the radio. Adjusted the accu-speed per the directions and took it for a test drive. Still no change. The directions say to adjust the knob 6 1/4 turns. I can adjust it 15 turns either clockwise or CCW and it will not affect the speedometer at all.

Out of curiosity, I cut the Gry/Blk (pin 14) wire at the Gem to see if my speedometer would quit working. It STILL works. I got under the truck and pull the connector off the sensor thats nearest the tail housing on the trans. BAM, speedometer no longer works! Alight, so where the heck is this VSS wire that I need to tap into? I can't find a pinout diagram for my '02 GEM module or PCM. Any help?!
 


gw33gp

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I just recalibrated my speedometer with a Dakota Digital Recalibrator. I had to take the instrument cluster out and tapped into the gray/black wire that goes to the speedometer behind the instrument cluster. I have a write up giving more details. You should be able to do a search on this Forum for "Dakota Digital" if you would like to see what I did.

I was more concerned about getting the odometer right and it is within 0.2% now. The speedometer is about 2 mph fast under 50 mph and gets closer to correct above 50.
 

tsayyote

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Well, I installed it on the gry/blk white on the black connector on the back of the instrument cluster and it works! Thanks!

Unfortunately, somewhere while I was installing this, I developed the dreaded high idle issue. Idles at 1200rpms now and with a slight tap of the throttle it revs up to 2000rpm for a few seconds and then drops down. Also holds 3000-3500rpm while driving and pressing in the clutch and wont come down until the truck stops. My last ranger had this issue and I couldn't figure it out, that I just sold it. I'm wondering if I damaged the PCM during my install. :icon_confused:
 

RonD

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Well, I installed it on the gry/blk white on the black connector on the back of the instrument cluster and it works! Thanks!

Unfortunately, somewhere while I was installing this, I developed the dreaded high idle issue. Idles at 1200rpms now and with a slight tap of the throttle it revs up to 2000rpm for a few seconds and then drops down. Also holds 3000-3500rpm while driving and pressing in the clutch and wont come down until the truck stops. My last ranger had this issue and I couldn't figure it out, that I just sold it. I'm wondering if I damaged the PCM during my install. :icon_confused:
With engine idling high unplug the IAC(idle air control) valve's wires.
See if idle drops, if it stays high then PCM is not doing it, most likely a Vacuum leak, a pretty good one(bad one) too.
If you remove the IAC valve to clean it, before you put it back on, turn on the key and IAC valve should open all the way(for starting), turn off key and it should close all the way(no power).

Also check throttle return, make sure you can't manually close the throttle more making idle lower.
 
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tsayyote

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2.3L
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Manual
With engine idling high unplug the IAC(idle air control) valve's wires.
See if idle drops, if it stays high then PCM is not doing it, most likely a Vacuum leak, a pretty good one(bad one) too.
If you remove the IAC valve to clean it, before you put it back on, turn on the key and IAC valve should open all the way(for starting), turn off key and it should close all the way(no power).

Also check throttle return, make sure you can't manually close the throttle more making idle lower.
Just went out and unplugged the IAC while my engine was still warm. Completely fixes the high idle between shifts and returned the idle to the normal ~900rpm. I'll pull the IAC out tomorrow and see how it operates. With my scan tool I can see the tps is at 16.8%. When I have the IAC plugged in, if I barely touch the throttle the rpm's go from about 1100, straight to 2000. There is no middle, it's impossible to hold the engine at any rpm between 1100 and 2000. The rpm's jump straight up to 2000 rpms at ~18% tps. The little gap between 16.8% and 18%, there is very little change in rpms. Once the tps hits 18%, it's right up to 2000rpms and it will stay there for 2-3 seconds after I take my foot off the throttle. With the IAC unplugged, the truck operates normally at any rpm. I still suspect the PCM, but i'll do as much diagnosis as I can before I drop $$ on anything else.
 
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