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Discussion Starter #1
I have a 1990 CTD n/ic and i was wondering because my speedometer flickers around like it has ADHD so i was wondering what sensor actually controls the speedo and where its located and the sensor that plugs into the top of the rear differential is broken and i was jw what the function of that sensor is.
 

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The sensor on top of the rear axle is the ABS sensor. I wouldn't worry about it.

I thought the 90 models were cable operated speedo's???
 

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Discussion Starter #3
ya they probably are but now im wondering where does that cable go so i can check it and what would make it bounce around like that sometimes it works
 

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On my 91 the speedo is run by the vss or vehicle speed sensor. It is located on or near the tailhousing of your transmission. They cost around $40. I know this because my speedo is doing the exact same thing right now! Sorry, no pics.
 

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On your 4x4 check that reducer box that the cable or VSS would screw into. It has been known for them to strip the gears from old age. It is screwed onto the transfer case. The the cable/VSS screws into it.
 

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Discussion Starter #6
how would i know if that is indeed the problem can i pull it out and how difficult is it to do:yourock:
 

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It just unscrews out off the transfer case adapter. Then you just turn one of the drive pins and gently hold the other one. If you feel any jumps or dead spots while turning it. Then it is bad.
 

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Discussion Starter #10
I have a getrag 5-speed will it still be the same?
 

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Yes it will. The 4x4's are the same it doesn't matter if it is a stick or auto.

A 2WD doesn't use that reducer box setup.
 

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1990s had a split- Bill's 90 donor rig had a cable, my 90 that was a driveway ornament for a year had the VSS.

2wd manuals have a reducer box, just not the same style as the 4x4.

Dan
 
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