Speedometer / Odometer Not Working. Read entire post.

Ryan Lawson

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Ok, so my speedometer and odometer are not working. All other gauges work correctly. I'm sure this question has been asked several times, but I cannot find a solution to my problem. Here's what I've done so far.

1. Changed out the worm & drive gear inside instrument cluster. No change.
2. Removed VSS and looked inside. Gears look fine.
3. Hooked VSS up to volt meter and spun with drill. It pulled 9 volts at a fast speed.
4. Pulled speedometer part of cluster from junkyard. Replaced the tiny motor the worm gear installs onto. No change.
5. Purchased new harness that plugs into VSS. No change.
6. Saw on google that the 15A fuse that runs the dome light may affect the speedo (not sure if that's true). Checked it anyway and it's fine.
7. Pulled passenger kick panel where the ECU is and located the pink/orange wire and gray/black wire that go to the VSS. Just wiggled them, kind of scared to mess too much in there. No change.

After all that, the only thing I can think of is the small control board for the speedometer inside the cluster may be bad. I have one from the junkyard but I really don't want to change that because the needle has to come off. On my last mustang I changed the overlays and the needles never were right again.

So, my questions are:
1. (obviously) Am I missing anything?
2. Can someone give me more detail on where the wires run from VSS to kick panel? I saw a post on ford460 forum where someone replaced the wires completely, but the guy was extremely vague.
3. Should I go ahead and replace the VSS just to see?
4. If I have to replace the control board, can someone give me detailed instructions on how to do it without screwing my needle movement?

My car is a 1994 cobra. 302 bored .030 over with DSS forged pistons. Trick Flow kit w/ cam. BBK shorty headers & cold air intake. 3.73 rear end gears.

Sorry for the long post, and thanks for any help.
 

evilcw311

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Ok, so my speedometer and odometer are not working. All other gauges work correctly. I'm sure this question has been asked several times, but I cannot find a solution to my problem. Here's what I've done so far.

1. Changed out the worm & drive gear inside instrument cluster. No change.
2. Removed VSS and looked inside. Gears look fine.
3. Hooked VSS up to volt meter and spun with drill. It pulled 9 volts at a fast speed.
4. Pulled speedometer part of cluster from junkyard. Replaced the tiny motor the worm gear installs onto. No change.
5. Purchased new harness that plugs into VSS. No change.
6. Saw on google that the 15A fuse that runs the dome light may affect the speedo (not sure if that's true). Checked it anyway and it's fine.
7. Pulled passenger kick panel where the ECU is and located the pink/orange wire and gray/black wire that go to the VSS. Just wiggled them, kind of scared to mess too much in there. No change.

After all that, the only thing I can think of is the small control board for the speedometer inside the cluster may be bad. I have one from the junkyard but I really don't want to change that because the needle has to come off. On my last mustang I changed the overlays and the needles never were right again.

So, my questions are:
1. (obviously) Am I missing anything?
2. Can someone give me more detail on where the wires run from VSS to kick panel? I saw a post on ford460 forum where someone replaced the wires completely, but the guy was extremely vague.
3. Should I go ahead and replace the VSS just to see?
4. If I have to replace the control board, can someone give me detailed instructions on how to do it without screwing my needle movement?

My car is a 1994 cobra. 302 bored .030 over with DSS forged pistons. Trick Flow kit w/ cam. BBK shorty headers & cold air intake. 3.73 rear end gears.

Sorry for the long post, and thanks for any help.

I had to replace my cluster. Everything worked great but the spedo. It would go all crazy every now and then and one day it just stopped working.

Few others have had the spedo just randomly die as well and replaced clusters to fix it. I think it’s the copper trace map on the back that just starts deteriorating that causes it.


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Ryan Lawson

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I had to replace my cluster. Everything worked great but the spedo. It would go all crazy every now and then and one day it just stopped working.

Few others have had the spedo just randomly die as well and replaced clusters to fix it. I think it’s the copper trace map on the back that just starts deteriorating that causes it.


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Ok, thanks. I was hoping to avoid that because people want an arm and a leg for cobra clusters. Does any cobra cluster from 94-04 fit?
 

Werecow

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There is a break in years but I'm not sure where the break is, I've seen it posted on here before. If I can remember or find who it was I'll bring them up cause they mentioned changing the pinout from one year to another.. this is for a GT, not for sure if Cobra's are different tho or not... Found the member, it's @BigBore96 but I can't remember what thread it was.. may try looking up by him to see what I'm trying to find.. I did find tho 94-95 had their own dash thing, when mustangs went to Mod motors something in the dashboard changed so that's a start there...
 
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Ryan Lawson

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There is a break in years but I'm not sure where the break is, I've seen it posted on here before. If I can remember or find who it was I'll bring them up cause they mentioned changing the pinout from one year to another.. this is for a GT, not for sure if Cobra's are different tho or not... Found the member, it's @BigBore96 but I can't remember what thread it was.. may try looking up by him to see what I'm trying to find.. I did find tho 94-95 had their own dash thing, when mustangs went to Mod motors something in the dashboard changed so that's a start there...

Thank you. Theres a place close to me that supposedly repairs clusters and the circuit boards in them for $100. I may call them and see what they have to say. There is a 94/95 cluster on ebay for $419. Ouch


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evilcw311

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Thank you. Theres a place close to me that supposedly repairs clusters and the circuit boards in them for $100. I may call them and see what they have to say. There is a 94/95 cluster on ebay for $419. Ouch


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Damn they’re getting high. I only paid $125-150 for the 2 I got.

If someone can redo the tracing on the back then it would be worth $100.


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Ryan Lawson

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Damn they’re getting high. I only paid $125-150 for the 2 I got.

If someone can redo the tracing on the back then it would be worth $100.


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Yea the prices for them are ridiculous. I'm gonna call the place tomorrow and I'll update you


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Werecow

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Yeh the 94 I had had on place burnt on the circuit on it,the plastic film I guess it is? And I traced it down to the lighting circuit for the dash lights but the whole dash was dead.. nothing on it worked at all.. I saw it work one time and I double checked the harness that plugged in it as well. I got fussed at by the guy who bought it back too, like I did something to mess it up... I was trying to figure out why it didn't work in the first place when he sold it to me!!
 

Ryan Lawson

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Update: The place near me called "circuit board medics" says they aren't equipped to test the circuit boards on my year model. What a joke.


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Werecow

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Circuit board is a circuit board.. it doesn't have a model year on it, that doesn't make any sense... Don't understand where they would get that from...
 

Ryan Lawson

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Circuit board is a circuit board.. it doesn't have a model year on it, that doesn't make any sense... Don't understand where they would get that from...

Sounded like BS to me. I'm gonna buy a VSS from advance and pray that fixes it so I don't have to go further.

I found this on an old thread. I guess that will be my next step. I really don't want to pull the needle off the speedometer to change the circuit board.IMG_0954.png
Do you know if the ignition switch has to be on to test these wires?


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Werecow

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If checking continunity you don't want power on the circuit... You're just checking for contact from end to end on the circuit and don't need juice on it..
 

Ryan Lawson

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If checking continunity you don't want power on the circuit... You're just checking for contact from end to end on the circuit and don't need juice on it..

Ok that's what I thought. Thank you


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Rtfm

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Wow, this is the perfect subject. Glad I saw it.
I also have a speedometer from my 95 GT that just stopped working. I had just finished installing a new sound system and alternator. Speedometer was inop after final wiring and panels replaced.

Cruise control works, so I figured I might have disturbed the grounds connecting the Vss return signal on the cluster connector somehow. It turns out the ground from pin 11 (pink/orange) on C250 is reading 6 ohms or more. It should be 1 ohm or less. The other ground on pin 2 also seems to be around 5 ohms or more. I don’t know where they terminate and that is driving me crazy. Anyone have any ideas?

I cannot sense the Vss voltage signal on pin 12 with reference to any ground on C250, but I can see the AC voltage when referencing ground. Hmmmm. I tried running the speedo with a jumpered ground, but I’m not sure I got a good connection. I’ve pulled the cluster and speedometer and I’ll try running it on the bench when I get the Vss sensor pulled out of the car. I don’t have a handy AC low voltage source to test with.
However, I suspect the IC on the circuit board has failed. I have tested the other components and they seem to be OK. I have also FINALLY sourced the chip. Problem is, it costs $42 and they sell in quantities of 5 minimum. I have not found any repair shop that advertises repairs on this cluster other than the odometer gears.

Please send a picture of your board with the IC showing the number or confirm that it is also N7100010FSCAGA. If so, I can replace the chip on both If yours is bad or anyone else has a bad Speedo they would like repaired. We could all split the cost of the chips. I just don’t feel like throwing over $200 at this one speedo right now.
Also, I can tell you how to bench test yours or you can send it to me and I can check it for you.
 

Ryan Lawson

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Wow, this is the perfect subject. Glad I saw it.
I also have a speedometer from my 95 GT that just stopped working. I had just finished installing a new sound system and alternator. Speedometer was inop after final wiring and panels replaced.

Cruise control works, so I figured I might have disturbed the grounds connecting the Vss return signal on the cluster connector somehow. It turns out the ground from pin 11 (pink/orange) on C250 is reading 6 ohms or more. It should be 1 ohm or less. The other ground on pin 2 also seems to be around 5 ohms or more. I don’t know where they terminate and that is driving me crazy. Anyone have any ideas?

I cannot sense the Vss voltage signal on pin 12 with reference to any ground on C250, but I can see the AC voltage when referencing ground. Hmmmm. I tried running the speedo with a jumpered ground, but I’m not sure I got a good connection. I’ve pulled the cluster and speedometer and I’ll try running it on the bench when I get the Vss sensor pulled out of the car. I don’t have a handy AC low voltage source to test with.
However, I suspect the IC on the circuit board has failed. I have tested the other components and they seem to be OK. I have also FINALLY sourced the chip. Problem is, it costs $42 and they sell in quantities of 5 minimum. I have not found any repair shop that advertises repairs on this cluster other than the odometer gears.

Please send a picture of your board with the IC showing the number or confirm that it is also N7100010FSCAGA. If so, I can replace the chip on both If yours is bad or anyone else has a bad Speedo they would like repaired. We could all split the cost of the chips. I just don’t feel like throwing over $200 at this one speedo right now.
Also, I can tell you how to bench test yours or you can send it to me and I can check it for you.

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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Werecow

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Dunno if it's related to what youse guys are talking about or not, but there is a resistor, that the alternator has to run thru in order for the charging system to work correctly that is located in the back of the dashboard. That's popped up here a time or two as well. I'm not as up on it as someone like @ttocs or @evilcw311 would be but I remember it..
 

Mike’s

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Check with www.myairbags.com located in Buford Ga 855-770-4055 they do ECU,Instrument cluster, ABS ETC, repairs for a reasonable price. I have used them for a cluster repair but not for a 94.
 

Ryan Lawson

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Dunno if it's related to what youse guys are talking about or not, but there is a resistor, that the alternator has to run thru in order for the charging system to work correctly that is located in the back of the dashboard. That's popped up here a time or two as well. I'm not as up on it as someone like @ttocs or @evilcw311 would be but I remember it..

Ok thanks, i'll check it out


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