When I bought my jeep the speedo didn't work so I started looking into the problem, I tried cleaning up the traces with an eraser but that didn't help. Next thing I did is say the hell with it and I ran three wires to the back of the speedo, one to the IGN post from the blue and white stripe wire, one to the SP post from the white with an orange stripe wire and one to the GND post from the black wire at the connector. The speedo sorta worked it would go up to 40mph when I started to move and stay there no matter how fast I was going the when I would stop it would back down to about 25mph. Turn off the Jepp and it would drop to 0mph.
I figured there must be some resistors or something that I had bypassed so I went a got a trace repair pen and repaired all the traces for the speedo, but now it is doing the exact same thing. Does anyone have any idea what could be the problem? I am at my whits end with this thing.
I think I might have screwed up the speedo wiring it direct like I did, but I hope I didn't.
As Que just said, I'd pull the sensor (would have done that way first, before wires) and check to see the plastic gear is not buggered, then insert it properly for the gear tooth count (the sensor has three positions). If not properly clocked, it either won't read, or will bugger the gear teeth.
Ok the sensor is hooked up and appears to be clocked correctly so I decided to just buy a new sensor. So I get the new sensor hooked up and solder the wires for the new connector (only god knows why they couldn't use the stock connector) take it out for a test spin and it is doing the exact same thing. Any more ideas of what could be wrong, I'm ready to go get a speedo and try that. Before I do that though I'd like to exhaust all other options. This thing is driving me nuts!!
Ok the sensor is hooked up and appears to be clocked correctly so I decided to just buy a new sensor. This thing is driving me nuts!!
Yes, it will do that (drive you nuts) if you keep buying parts on speculation. Use diagnostic skills before your wallet. How about measuring things? With the key on, one of the three lines to the sensor should be ground, another constant power (8-12V), and the third is the signal line, which should show some activity on a meter when driving.
When I was first messing with it, I used a multimeter and had one line that was 12v and one that was about 5v at idle and when I moved it dropped to about 2.6v and the third line was a ground.
That would be fine, you got signal output with proper voltages in, which indicates you didn't need a sensor. Sure enough, replacing it didn't help. Next verify that the signal at the dash is the same as the sig out at the bottom. If so the sig lines and sensor are fine, and look at the gauge cluster better.
Well got it working, I figured that I would just end up getting a speedo off of ebay so for the time being I would get all the lights working in the cluster so I took it back out and and went through the traces again and cleaned them up and redid the ones that needed it. put it all back together and low and behold the speedo started working, was something like 25 or 30mph off so I took the clear plastic off and repositioned the needle now it is something like 5mph off and I can deal with that.
I would like to thank everyone that helped me out on this issue... Thanx a million!!