speedometer help!!!!

[yetijeff]

so heres the problem. i have a 1990 hatch runs great pretty low miles, bone stock. a couple months ago i was driving with the cruise control and all of the sudden the cruise control shut off and the speedometer stop reading anything, went down to zero. now if i get above 3500 rpm in fifth gear (about 85mph) the motor either cuts fuel or ignition until it gets back down to about 3k. at first i thought it was just the vehicle speed sensor so the other day i swapped it for a brand new one. im still having the same problem. the funny thing is sometimes if ive been on the road for a half hour or so the speedo works momentarily as well as the cruise control, but then cuts out and does the same thing. if anyone has any clue as to why this is happening any help would be very appreciated. driving around town with no speedo is sketchy with the po po around here.

[Likethunda]

sounds like a short somewhere? not to familiar with Cruise control (my car doesnt have it)

just get rid of it =D

[yetijeff]

ya i thought that the cruise control might be it too, but i dunno how that could make the speedo not work??? its really aggravating

[mrchomponthis]

I believe its a yellow and red wire from ecu back probe it. see if there is a short.

[yetijeff]

thanx ima do that tomorrow

[yetijeff]

so i checked the wire from the ecu. doesnt seem to be a problem. could it just be the speedo is bad? also now i have the new vss it seems to work alot more frequently...

[ichisan]

More likely it's the speedometer in the cluster. I'm having the same problem in my 91 and I can get the speedo to work when I drive over certain bumps or if I slap the dash to get the needle to bounce a little bit. Lately, it's been more stubborn to get started however and I'm looking to find a replacement or maybe even trying to figure out how to fix the existing one.

I connected my speed sensor to a multimeter and checked for AC voltage. Voltage should go up when the car is moving and close to 0 when at rest.

Then I checked the connection going from the speed sensor connector all the way to the cluster and didn't find a weak connection either.

When the speedo stops working, I get a CEL, cruise control will quit and won't work, and the odometer stops. When the speedo does work, everything goes back to normal.

Looking at the wiring diagram and using the above troubleshooting methods, I deduced my problem to the speedometer. I've yet to find a replacement speedo or pull out my cluster but I'm sure it should work when I replace it.