Viper speedo testing?

Shrader

Shrader

New member
Joined
May 11, 2007
Messages
202
Age
47
Location
Post Lake, Wisconsin, United States
I have an 02 viper that he speedo does not work on, it just shoes 0 all the time. I have checked continuity from the harness to the speedo, and all wires are good (or at least have continuity), the previous owner installed a new sensor, and left the old one with the sled, which i also tried. I have an extra speedo unit from an rx1, and that does the same thing. There is power, and ground at the sensor harness also. Is there a way to test the speed sensor itself? as in, is there a way to ohm it? drive bearings, and reluctor wheel are also in perfect shape. Any idea what might be wrong?
 

You can jack up the back of the sled and give it some gas so the track starts spinning, just make sure it's secure. Also make sure the sensor is close enough to the gear. Installed mine last year and it just read zero, found out it was because the sensor wasn't close enough to the gear on the end of the driveshaft.
 
There's very little play. I just loosened up the bolts pushed as far forward as possible and retightened them. You can test the sensor out too by unbolting it, taking the gear off the drive shaft and putting it in a drill and spinning the drill (with the gear in it) close to the sensor. If it registers a speed when you hold it close your issue is one of sensor spacing like I mentioned.
 
yes, I have tried both sensors, the original was in a bag in the trunk when i got the sled, previous owner said he replaced it, and it still didn't didn't work. I have tested all wires, as I said above.
 
Have you tested for wires from the speedo not just the sensor? Not sure if your aware but the viper engine tends to rub on the wires causing some of them to "rubthrough" If both sensors don't work and you've tested the wires from the sensor, I would next check wires under the engine for signs of rub through or check wires at the back of the tach/speedo to the End of the harness for continuity. I've read a few threads on this subject when it happened to me, it's always either the sensor, harness rub through or a faulty speedo.
 
yes it can be tested.

unplug the connector and attach the + lead from your multi tester to the white lug on the plug. hook the negative up the the black/green. in addition, you will need to use a 12v power source with the + connected to the blue/yellow lug and the negative to the black/green.

now, with the track elevated, slowly rotate it and you should see a voltage cycle per rotation from .6v to 4.8v with the meter set at dc5 volts.
 
This is a test for at the speedometer head correct? If so that does not tell me anything because i already know the speedo itself is good. What i need is the test proceedure/specs for the speed sensor itself, as in bench test if there is such a thing?
 
I took my sensor over to a buddies, and installed it on his rx1, and it works fine, so I have eliminated the speedo head unit, and speed sensor as the problem. Next question is, even though I have continuity in the wires from the sensor to the head unit, is there a certain ohm the wires need to be? and what should the voltage at the sensor be?
 
the procedure i listed is directly from the yamaha service bulletin for the speed sensor. the head unit yamaha has a special wire harness to tap in and power up for testing.

most likely you have a wire rub through between the stator and cdi, the cdi and the main harness, or anywhere before or between the plug your testing for continuity. yes, you can have continuity from plug to head unit, but there has to be a signal from your electrical system to power things up. rub throughs and bad stators are not uncommon to the viper.

as for specific voltage i would have no information as yamaha doesnt have or list that info. its a go or no go with the testing and as you have done to rule out the individual components. from here, your working your way back to the stator. a wiring diagram may be beneficial to your needs, but off the top of my head i would be looking at the blue wire with the white stripe. seems like thats where it was on the last one i diagnosed.
 
Thanks.

I now think that both of the speedos i have are non working. The "spare" i have, i found in the woods at a crash sight. I took it to my buddies this morning, and the speedo does not work when plugged into his apex(06) or his vector (also an 06). I am taking my original over to a differnt Guy's house to try on his working viper before i tear into wiring issues. I tested the pulse wire (pink) at the sensor (whire) at the speedo, and have .13v at idle up to .44v while turning the track.
 
found a wad of wires under the engine that were smashed together, one was broken, fixed all of those, and wrapped with a protective sleeve, put sled all back together, and still does not work, back after it again this week, had to leave the garage before I wrecked something.
 
I think tonight, I am going to run new wires from the sensor to the speedometer, it looks like they go straight from the sensor to the speedo, so that should take care of the issue. Will post update later.
 
is it as easy as the ground wire for the sensor is not good? the 2 wires do go straight to the gauge but theres a ground wire for the sensor and the guage that goes in like 3 differnt grounds for the meter.

I understand your frustration, wiring will test a mans patience level quickly....lol
 
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