Needsdiesel

So been through alot of really good forms on this site!! but with all the help still no fix.

So first on purcase of this truck the speedo did not work along with the brake and ABS light on plus while driving the bell goes off at the same time fuel gauge drops to E then comes back to normal???

Over time i put a junkyard axle in the rear with new speed/ABS sensor and tone is good so is moving speed tone 2000oms to 0oms still no speedo?

A little confused on some info i get from some people about the speed sensor. the wireing diagram i got from ondemand5 shows a speed sensor in the tranny and the diff, so the diff is ABS/speed till 50k or so and then tranny sensor takes over? the dealer don't even have it on there parts program? will be swiching it with my old tranny sensor?to see if it fixes problem
Second the ABS sensor in the rear must not be the only one how would it know when to do its job? there are non on the front could this be the tranny one?

For the brake and ABS light i could care less but the "dinging" i will find you and
This truck is a 98, club cab, long box, 2500, 4x4, 5.9 12v

Thank All!!!!!

98fargo

I've heard also that there is two speed sensors in '98's but mine only has one in the rear diff, so I am interested to find out more about this!

Needsdiesel

My 97 1Ton has the speed sensor in the t-case and for the longest time the ABS light was on! found the problem the wire had broke at the diff! fixed wires and light went out! funny. still stumpt on the ABS so you hit the brakes and the front tires skid!! what tells ABS the tires are skidding if there is only one sensor? in the rear diff? is ABS a farce in these trucks?? my next few days are going to be with my head jamed! in the wiring I will let you all know my find!!

98fargo

These trucks have a fairly crude abs system, I'm guessing yours only has rear wheel abs (was four wheel abs available on them?) which means the front will still lock up, the sensor on the diff is what tells it to work or not, if it had front abs as well there would be a sensor on each front wheel

infidel

Both my '95s have 4w ABS.
It was an option starting in '94

98fargo

Thanks good to know, I wasn't sure!

9812vram

Transmission speed sensor sticks out of the side of the OD case. My '98 has that and the one in the diff. I don't know how the ABS works...

98fargo

That's interesting about having two speed sensors, mine just has the one in the diff, I swapped mine to a nv4500 from an auto and defiantly nothing in the tranny or transfercase, now I'm curious why some have two and some don't......

infidel

'98 have two sensors.
One measures under 30 mph, the other faster.

98fargo

That must be one of those anomalys in vehicle production, goes to show you nothing is "standard" as my 98 defiantly only has the one sensor, I always find quirks like this interesting, can make troibleshooting some stuff interesting!

infidel

It may be the '98 two sensor system is only for 4w ABS.
I've never checked it out closely.

98fargo

Maybe that is why, I'll have to dig out some wiring diagrams and have a look, now I'm curious if mines just an oddball or if there is an option that affects that like you say maybe 4wabs.

9812vram

Here's a cut n' paste of what OnDemand5 says about it....

Quote:
"OUTPUT SHAFT SPEED SENSOR
Output shaft speed sensor is located on overdrive unit attached to rear of transmission. Output shaft speed sensor is mounted above the lugs on park gear in the overdrive unit. Speed sensor input signals are generated
when lugs on park gear rotate past face of sensor. Input signals are delivered to PCM. The PCM uses this input signal for controlling transmission operation. The Vehicle Speed Sensor (VSS) also serves as a back-up to the output shaft speed sensor. The VSS signal is also shared with the PCM.
NOTE: Output shaft speed sensor may also be referred to as transmission shaft speed
sensor or shaft speed sensor."
End Quote

VSS is the Vehicle Speed Sensor found on the rear Diff.

It doesn't say anything about ABS. The diff in speed between the Trans Output Speed (OD Case) and Vehicle Speed (Rear Diff) should always be the same shouldn't it? It says in the ABS section that there is a tone ring and sensor for each front wheel on the 4 wheel ABS systems. I don't get how it works.

Oh ya, and as far as I know, my truck is only Rear Wheel ABS and it has both the Trans Output Speed and Vehicle Speed Sensors....????

Needsdiesel

Thanks 9812vram you definatly know your way around ondemand5 better than i do!

And so you all know the changing the sensor and a little wire repair in the OSSS fixed ALL!!! ABS/Brake/Cruzz/dinging/fuel gauge.

Thank you all for your knowledge and research, SWEET!!!

98fargo

Glad you got it fixed!!