Speedo malfunction
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New User
Joined: Jan 2007
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Speedo malfunction
Hello Everybody, I just bought a 95 awd astar and the speedo needle is jumping around wildly anyone familar with this problem or know of wiring diagram or proceedure for troubleshooting?
Thank!
Thank!
Senior User
Joined: Apr 2004
Posts: 312
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From: Lanham,MD
My 95 AWD did the same thing. I change the instrument cluster with one from junk yard after deal quoted me $300.00. $10 at the you pick it yard in my area. One of the VSS(vehicle speed sensor) could cause it too.
Lead Driver
Joined: May 2003
Posts: 9,303
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From: Lyndonville, Vermont
https://www.ford-trucks.com/forums/5...soldering+iron
Some more info. When does it jump and at what speed? Does it get worse at higher speeds?
Dick
Some more info. When does it jump and at what speed? Does it get worse at higher speeds?
Dick
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New User
Joined: Jan 2007
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Speedo Malfunction
Yeah the needle is solid until 45-50 mph then jumps around seems to get worse the faster you go. Am doing a visual inspection of speed sensor and tone ring today. Do you know what goes wrong with these things don't seem to be a common problem?
Lead Driver
Joined: May 2003
Posts: 9,303
Likes: 48
From: Lyndonville, Vermont
Try this. Unplug the abs module under the ash tray..Try it..Let me know if its any better. If the tone ring gets a tooth bent or chewed it will screw the needle up..I still have issues with my 96 I changed the cluster then the tone ring and bearings the needle was bouncing over 60 mph 70 it would go nuts..Now it doesn't go nuts but if I unplug the abs module it get rock solid...
Dick
Dick
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Post Fiend
Joined: Apr 2005
Posts: 5,720
Likes: 5
From: Washington state
look for corrosion in the rear speed sensor plug and socket
dropping diff pumkin plate, flush diff gears and housing with spray electronics cleaner which is fairly benign and won't damage seals... wipe out bottom of pumpkin housing with shop rags, no paper towels, they tear and leave pieces....
cleans out any metal wear particles that may be floating in the hypoid lube.....can cause false sensor speedo readings
exam tone ring on outside of ring gear for any damage or metal particles stuck in teeth....
use only an adhesive gasket sealer on old neoprene cover seal, both sides....Permatex 300 Super is the only thing i will use
stay away from the RTV goops....they make a bead on the inside which tears off and ends up as gum on the pinion teeth and in the bearings=not good
use a quality brand name 75w90 rear end lube only....the cheap house brand names don't hold up in heat and hvy use or for 100k miles....rear ends are made for synthetics...Amsoil 80w90 full PAO Severe Duty is the Right Stuff for small capacity poor air flow hvy loaded Aeros
dropping diff pumkin plate, flush diff gears and housing with spray electronics cleaner which is fairly benign and won't damage seals... wipe out bottom of pumpkin housing with shop rags, no paper towels, they tear and leave pieces....
cleans out any metal wear particles that may be floating in the hypoid lube.....can cause false sensor speedo readings
exam tone ring on outside of ring gear for any damage or metal particles stuck in teeth....
use only an adhesive gasket sealer on old neoprene cover seal, both sides....Permatex 300 Super is the only thing i will use
stay away from the RTV goops....they make a bead on the inside which tears off and ends up as gum on the pinion teeth and in the bearings=not good
use a quality brand name 75w90 rear end lube only....the cheap house brand names don't hold up in heat and hvy use or for 100k miles....rear ends are made for synthetics...Amsoil 80w90 full PAO Severe Duty is the Right Stuff for small capacity poor air flow hvy loaded Aeros
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Speedo Issues
Thank you members for posting replies on this one!
I had to replace the front and rear brakes before driving any further.I will try unplugging the abs computer under ash tray on my way to get silicon and gear oil for the rear end. Does anyone know should I disconnect the battery before the abs computer or is it necessary?
I had to replace the front and rear brakes before driving any further.I will try unplugging the abs computer under ash tray on my way to get silicon and gear oil for the rear end. Does anyone know should I disconnect the battery before the abs computer or is it necessary?
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New User
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Speedo Issue
When I pulled the rear end speed sensor there was a sliver of what looked like chrome. I am guessing the carrier bearings are failing. Sure enough I pulled the rear end cover (composite with two cracked bolt holes no wonder it was leaking) and there was metal on the cover magnet and in the bottom of the case. Happy there was no apparent damage to the tone ring. I cleaned it all up with electrical cleaner as suggested and refilled it. The speedo still starts jumping around 55mph and gets worse as the speed increases. Will unplug abs computer and retry today. Thanks Again!
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Most likely the problem is a cracked solder connection inside the instrument cluster. The vibration inceases as speed increases, the poor or broken connection causes the cluster to loose count of how many pulses it is getting per second from the sensor. So it starts jumping around, depending on how many successful count it got within the frame capture period. I do recommend unplugging the ABS computer, because that is free and involves very little work. IF that doesn't improve things, check out the solder on the instrument cluster. Chances are that the crack might be difficult to spot. Resoldering it should fix it if there is no damage to the traces. If the trace is damaged, you are best off soldering a piece of wire and bypassing the damaged trace (ie. alternate route.)
Lead Driver
Joined: May 2003
Posts: 9,303
Likes: 48
From: Lyndonville, Vermont
Khanty
The way it was explained to me by the folks who repair these things is if you get a wobble at 50 and above and it gets worse with speed then its the tone ring. I replaced mine and did the bearings. Helped alot but still not right. I realy would like to know why some do and some don't. I also replaced the cluster and speed sensor with no change. All the wires and grounds measured ok..Unplug rear anti lock module and its rock steady...Go figure not enough signal strengh to run two devices..I hav'nt given up.
Dick
The way it was explained to me by the folks who repair these things is if you get a wobble at 50 and above and it gets worse with speed then its the tone ring. I replaced mine and did the bearings. Helped alot but still not right. I realy would like to know why some do and some don't. I also replaced the cluster and speed sensor with no change. All the wires and grounds measured ok..Unplug rear anti lock module and its rock steady...Go figure not enough signal strengh to run two devices..I hav'nt given up.
Dick
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Perhaps there is an electrical leak that is causing a low voltage situation that in turn causes speedo malfunction. Our van used to have problems with the speedometer and odometer not working at all. Once we replaced the turn signal switch and the headlight switch, the problem went away completely. Three years and there are still no problems with either the speedometer or odometer.