hi again i was on this sight because i am having this problem abs and brake light also 26 mph is when my speedo kicks in( DISCLAIMER I KNOW THE SPEEDOSENSOR IS PROBABLY YTHE PROBLEM ANDMY DAD 40YR VET MECHANIC /HEAD MACHINER TOLD ME RIGHT OFF B4 I GOT TO THIS FORUMREAR SPEED SENSOR ) I believe you all have confirmed that but as not to trouble my dad anymore id like to figur the rest of this out myself (ten+ yrsof free service and 8 motorbuilds {not this 5.2} makes me want to give him a break ....differance is i have severly lost gas mileage could this be related? The enging still rocks and moves it ( the truck ), no lost power but my miles per gallon has dropped from about 12-13 to 7-8 mpg . right at the same time as this abs/brake light comes on . now i do run mobile 1 synthetic and have religiously since i bought it ( the only reason i believe that ol' 5.2 is still running ) ALSO HAVE AN AIR COMPRESSOR so the tires are ver'dat 47psi evry week simple but im just wondering if there is any thing you all might have noticed when this prob originaly started being posted or do i have another problem i also not previously listed converted old open differntil to a richmond powertax lockrite locker in winter of 04-05 ( hate getting stuck in snow) thanks in advance guys

 

How are you measuring your mpg? If you are using the overhead computer (if you have one), then I would say that the sensor is the fault. I am assuming the computer uses input from the speed sensor, but could be wrong. Basically, your gas mileage may not have dropped, but because the computer is getting faulty data, it shows a drop in mileage.

Get the sensor changed, then check your mileage. The best way to check mileage is by recording actual miles driven against gallons used. When you troubleshoot problems, test one thing at a time, then move on to the next item. If you have access to a scan tool or code reader, check your codes to see if you have a faulty sensor(s).

Good luck and welcome to the forum.

 

Thnks ash for the response but my truck is a stock 2x4 with rollup windows i dont have that fancy stuff, i'll keep it simple though my gas mileage calc is miles added on odometer divided by gallons to top off at each fillup so ...the old fashioned way gotta keep up on this incase your gas gauge goes out on a road trip so you know wether you should pass that gas station or pull in for gas and hoho's oh and a double red eye so you can man up and keep on rollin .

and amendment as to the sensor decision since i pout the new differential in and it behaves more like a locker than an open differential should i get the sensor for the 4X4? just a thought any ideas .

 

i think the VSS at the diff is the same for that axle.. as long as you took out a 9.25 rear end and installed a 9.25 rearend i would assume just get one for your truck.

you COULD go to the parts store and have them pull a 2X4 and a 4X4 VSS off the shelf and compare them..but i would be willing to bet they are the same.. same rearend used in all 1500's from 94 to 2001..change that first..

i think your odo might be affected by your vss, if you think about it.. your using gas from 0 to 26 mph (even more when you start out from a stop too) and your odo is racking up the miles driven untill you hit 0- 26. a simple test is find a place where you can drive 1 miles at speeds under 26 miles.. and your odo doesnt start ticking the miles.. then this is your problem.... so there for your getting less miles out of the tank your using.. makes sense?

 

You are 100% correct. The 20% mpg loss is to be attributed to the odometer being ina static condition (just like the speedometer) from 0-25 mph. Fix the Rear Wheel Speed Sensor and mpg will return to normal.

My speedo/odo quit entirely when my sensor went out. As a result, my mpg's dropped to ZERO. [8D]