Speedometer / Odometer Not Working. Read entire post.

[evilcw311]

The resistor has nothing to do with the spedo/odo. [mention]Werecow [/mention]


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[Werecow]

K wasn't sure if there was a possibility of it going out may mess something else up.. okees just a thought..

 

[Rtfm]

It may be the weekend before I can pull my cluster again. That would be awesome if you could explain how to bench test it. Also, what chip are you talking about exactly? Thanks


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This is the chip on the speedo. It is a 5 NOR input.

 

[Ryan Lawson]

This is the chip on the speedo. It is a 5 NOR input. View attachment 5926

Oh ok, I will let you know if its the same. I didn't even try to look for a new one I figured noone made them I pulled another one out of the junkyard. I think that the problem with mine is somewhere in that piece as well, but I am kind of a p***y about pulling the needle off cuz I don't know how to make sure it's calibrated correctly. Do you?

Also, how did you test to narrow it down to just the chip? I just pulled the whole control board from the junkyard? Let me know how you tested the board and how to bench test the speedo and I can give you some better info about mine. Thank you


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[Rtfm]

I checked the other components. The only remaining components not checked are the chip and X1. I’ll have to pull the crystal to see it’s frequency. The chip is a Signetics. No longer made, but some stock is out there, albeit for $42 each. There is a Philips chip of the same number, but comes from China. $3 with $25 shipping.

To remove the needle, pull the stop pin out and let the needle come to rest. I think you’ll find it ends up about 6 o’clock. Then pull the needle off. Straight pull and takes a little effort. It will come off.

 

[Ryan Lawson]

I checked the other components. The only remaining components not checked are the chip and X1. I’ll have to pull the crystal to see it’s frequency. The chip is a Signetics. No longer made, but some stock is out there, albeit for $42 each. There is a Philips chip of the same number, but comes from China. $3 with $25 shipping.

To remove the needle, pull the stop pin out and let the needle come to rest. I think you’ll find it ends up about 6 o’clock. Then pull the needle off. Straight pull and takes a little effort. It will come off.

Ok, I pulled the one from my junkyard speedo and it had the same chip.

It came from a 94 as well so I'm 95% sure it's the same as my cobra. How exactly did you find out it was the chip that's bad instead of any other component? What is the testing method?

Also, I screwed the needle when pulling it off. Can you send me some pics or video showing how to take it off without messing it up? And how to replace it and it be in the correct spot.

Thank you


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[Orl1mjf]

FYI, for all the gauge needles that lose adjustment when disconnected, I’ve always found the easiest way to get them back to normal is leave the lens cover off, with the needles just barely on, start the vehicle. You can adjust the oil pressure and volts to wherever they normally would be, once the car is at normal operating temp, adjust that needle and then press it into position. For your speedometer, use your gps function on phone to tell you how fast your going, then adjust your needle to match.

 

[Rtfm]

Just pull straight off is the best advice I can give you. Mine stabilized at the 6 o’clock position before I pulled it. I’ll worry about calibration when it goes back.
I haven’t confirmed my cluster is dead, yet. I just tested all the other components except the chip and that blue crystal labeled X1, just left of the chip. The other components are rather robust and I had a leaky capacitor that I replaced. It was not the problem, though.
I need to verify the chip is bad by putting the correct ac signal to the speedo input, the ‘sig in’ on the back. I need to get the sensor out of the transmission in order to spin it up on the bench and provide the correct signal for a test to verify my board is either good or bad. If bad, it must be the chip.
Can you photograph the blue component to the left of the chip and post? I see yours has the value printed on the left where it can be seen. That will let me see the frequency reference.

 

[Rtfm]

Oh, I just noticed your board is lacking the two bipolar electrolytic caps. Was that from a 120 mph speedo for a 6 cylinder?

 

[Ryan Lawson]

Oh, I just noticed your board is lacking the two bipolar electrolytic caps. Was that from a 120 mph speedo for a 6 cylinder?

It may have been a 6 cylinder, that is the one from the junkyard. When I get back to the shop I will take a picture again


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[Ryan Lawson]

FYI, for all the gauge needles that lose adjustment when disconnected, I’ve always found the easiest way to get them back to normal is leave the lens cover off, with the needles just barely on, start the vehicle. You can adjust the oil pressure and volts to wherever they normally would be, once the car is at normal operating temp, adjust that needle and then press it into position. For your speedometer, use your gps function on phone to tell you how fast your going, then adjust your needle to match.

Thank you


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[Ryan Lawson]

Just pull straight off is the best advice I can give you. Mine stabilized at the 6 o’clock position before I pulled it. I’ll worry about calibration when it goes back.
I haven’t confirmed my cluster is dead, yet. I just tested all the other components except the chip and that blue crystal labeled X1, just left of the chip. The other components are rather robust and I had a leaky capacitor that I replaced. It was not the problem, though.
I need to verify the chip is bad by putting the correct ac signal to the speedo input, the ‘sig in’ on the back. I need to get the sensor out of the transmission in order to spin it up on the bench and provide the correct signal for a test to verify my board is either good or bad. If bad, it must be the chip.
Can you photograph the blue component to the left of the chip and post? I see yours has the value printed on the left where it can be seen. That will let me see the frequency reference.

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[Rtfm]

Ok, I pulled the speed sensor and applied the input to my speedometer board. No signal getting to the coils, so the chip or the crystal frequency reference (X1) is bad. I’m betting on the chip.

 

[Ryan Lawson]

Ok, I pulled the speed sensor and applied the input to my speedometer board. No signal getting to the coils, so the chip or the crystal frequency reference (X1) is bad. I’m betting on the chip.

Where are you located? I am close to Spartanburg, South Carolina. If you are within a manageable drive and can fix the speedos I'll split the cost of the chips with you. Order the 5 chips and see if you can fix yours. If it works I'll come to you and give you $105 for half the chip cost and pay you extra to fix mine. I'll take the chip to fix mine and one more, and you keep 3.


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[Ryan Lawson]

Ok, I also want to double check that all the wiring is good and power is reaching the cluster. I have this wiring diagram:

I need someone with a little more electrical knowledge to shed some light on this. Maybe Rtfm?

Questions:

Where are the G103 and G201 grounds physically located?

How do I test to make sure there isn't a problem in any of this wiring?

How is the speedo connected the the ECU and how do I test that connection?


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[Rtfm]

Excellent questions, Ryan. I have looked for the grounds and haven’t found them, yet. I would love to know, as well. C106 is the connector under the hood on the firewall in front of the passenger seat. You can trace the wires to that connector on the way to the ECM, I think. My cruise control worked, but I was also having trouble getting the AC signal on pins 11 and 12. I could reference the voltage against another ground, however. It looked like my pin 11 and other grounds on C250 were bad. It’s a frustrating combination to chase down.

Have you tried to use your cruise control to see if it works. If so, the speed sensor is functioning and the signal is getting to the ECM. Now, to test for signal to the C250 connector, connect a voltmeter for AC voltage across the pins for the signal at the connector, pins 11 and 12. You should see a voltage up to 7-9 volts, but more like 2-3 volts around 20-30 mph. If the signal is there, then your wiring should be good and the speedometer board is suspect. You can measure the resistance of the coils in the motor on the board. They should be around 187 ohms if good. S- to S + and C- to C +.

I am located in TX in the DFW area. I’ll let you know if I get those chips. I’m looking for a junker similar type Ford cluster from a similar year instrument cluster in other models right now and having difficulty finding any repair shops that will answer the phone to see if they have a lead on this chip.

 

[Ryan Lawson]

Excellent questions, Ryan. I have looked for the grounds and haven’t found them, yet. I would love to know, as well. C106 is the connector under the hood on the firewall in front of the passenger seat. You can trace the wires to that connector on the way to the ECM, I think. My cruise control worked, but I was also having trouble getting the AC signal on pins 11 and 12. I could reference the voltage against another ground, however. It looked like my pin 11 and other grounds on C250 were bad. It’s a frustrating combination to chase down.

Have you tried to use your cruise control to see if it works. If so, the speed sensor is functioning and the signal is getting to the ECM. Now, to test for signal to the C250 connector, connect a voltmeter for AC voltage across the pins for the signal at the connector, pins 11 and 12. You should see a voltage up to 7-9 volts, but more like 2-3 volts around 20-30 mph. If the signal is there, then your wiring should be good and the speedometer board is suspect. You can measure the resistance of the coils in the motor on the board. They should be around 187 ohms if good. S- to S + and C- to C +.

I am located in TX in the DFW area. I’ll let you know if I get those chips. I’m looking for a junker similar type Ford cluster from a similar year instrument cluster in other models right now and having difficulty finding any repair shops that will answer the phone to see if they have a lead on this chip.

Thank you for the info. I'll keep you updated on what I find.


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[proudgeek]

Chek the gear in the speedometer cable where it connects to the transmission just in case the issue is mechanical. It will take 10 minutes or less...

In case it needs to be replaced:
https://lmr.com/products/Mustang-Speedometer-Gear-Calculator

 

[Ryan Lawson]

Chek the gear in the speedometer cable where it connects to the transmission just in case the issue is mechanical. It will take 10 minutes or less...

In case it needs to be replaced:
https://lmr.com/products/Mustang-Speedometer-Gear-Calculator

Thank you. I already replaced the gear on the vss because I installed 3.73 gears. The gear inside the transmission looks fine.


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[Rtfm]

Ryan, check the cruise control function to see if the signal gets to the ECM. The signal from the speed sensor goes straight to pins 11 and 12. See if you can get a low resistance (less than 1 ohm) path against a ground from pin 11. Check with an AC voltmeter across pins 11 and 12 when the car is in motion to check for a signal voltage. It should read over 1.5 volts or better with a forward speed of 10 mph or more. If you have no signal between those pins, check pin 12 and a good known ground for the AC signal from the speed sensor. If no voltage, then remove the sensor from the transmission and spin it up using a drill and you should get 6-9 volts out of it easily. If no voltage that way, the sensor is bad.
I can walk you through testing the speedometer on the bench, too. If you have signal across pins 11 and 12, then your speedometer should work if you are getting power from fuse 8 to the switched power (pin 16) and constant power through pin 13.