North American Turbocoupe Organization



newbie help with inop speedometer
fl tc bird Offline
Junior Member
#1
Hi guys, new to the forum, and have a very nice 88 turbo 5 speed. Recently the speedometer stopped working, along with the odometer and the cruise control. I replaced the speed sensor on the trans with a new one, but still no luck. I did a search on the forum, but did not find any info on this. Any suggestions would be greatly appreciated, as I have to take the car on a 1000 mile trip up north next week and would really like to have a speedo and cruise for the trip. Thanks in advance.
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Not B Anymore Offline
Administrator
#2
Welcome to the board!

Have you checked the fuses? In particular fuse #17? It's all the way at the top of the panel next to the signal flasher.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
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fl tc bird Offline
Junior Member
#3
Thanks, will check that fuse tomorrow. What exactly does that fuse control?
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Not B Anymore Offline
Administrator
#4
It can affect both the speedo and cruise. The odometer won't work if the speedo doesn't work.
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
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fl tc bird Offline
Junior Member
#5
Thanks, fingers crossed and hoping that's it.
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Jeff K Offline
Administrator
#6
The issue is either with the VSS or the VSS wiring if speedo and cruise quit at the same time. Do you have access to any electronic test equipment? If you can get a signal generator, input a 100 Hz 5V signal into the VSS connector (harness side) with key on. Speedo and odo ahould work and speeedo will read around 40 mph. If you cant do that, pull VSS from trans (leave connected to harness) and check it in a variable speed drill and spin it. Speedo and odo should work. If they do, look to see if the VSS drive gear on the trans tailshaft is damaged. Can also check VSS output by checking it into a drill and spinning it while monitoring its output using a DMM that reads frequency or an oscilloscope, as the VSS is just a small electric AC generator.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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fl tc bird Offline
Junior Member
#7
Thanks Jeff, I do not have a signal generator, but as I said, the VSS was the first thing I replaced figuring that was the issue. I can get under there and pull it back out and connect it to my makita v/s drill and see if it will work. Which direction should I turn it? clockwise or counterclockwise? Would the drive gear in the trans really be that fragile as to break? Usually that gear is steel and the operation gear or drive unit is nylon?
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TurboCoupe50 Offline
Posting Freak
#8
The T5 use a nylon gear that is held on the output shaft with a clip...

When I got my red TC ready to sell I found it didn't have a working speedo OR 5th gear.. Dunno what kind of problems it had inside but since it also had a clutch issue, I sold it as is and included a known good T-5... A friend has it and speedo worked with the repl trans...

Somewhere around here I have a scope clip of the signal produced by a Ford speed sensor, but then I guess it won't do us much good...
1988 Turbo Coupe331 AOD

1972 Comet GT

1969 Fairlane Cobra 428CJ 4-Speed
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Jeff K Offline
Administrator
#9
It doesnt matter if you spin the VSS CW or CCW.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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fl tc bird Offline
Junior Member
#10
Thanks guys, I appreciate all the input. Raining like hell here today, so will not accomplish much today......
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