Archived Help! Abs, Brake light and no speedo!

[pwerwagn]

Hey guys, occasionally I've noticed the Abs light come on on my 98. this morning, the abs light came on at startup and didnt go off. when I got to the highway, I looked down and speedo read 0! I drove off the tach, and about 15 miles down the road, the brake light came on and all of a sudden, the speedo jumped to 50 (working), the abs light went off and the brake light went off. whats going on? Also, what could cause my seatbelt to lock after 30min? the seatbelt light comes on, and if i open the door it releases and the light goes off?

thanks in advance.

 

[Eric_77]

A loose fuse or wire hopefully. That is what my 92 would do (well everythig would stay on or dead) when TPS went out.

 

[AKAMAC]

More than likely it is your speed sensor on the rear axle. Check the connection for any corrossion first, it is located on top of axle housing. It's easy to replace.

 

[pwerwagn]

Thanks guys. I'll check that. It did it again this morning.

 

[Matt400]

Most likely bad speed sensor on the rear differential. Disconnect it and measure resistance across it. Should be 1300-1500 ohms. Its a Dealer part. #4485165 I think is the part number.

 

[pwerwagn]

Thanks for the info, I'll measure resistance today.

Just curious, why would it be intermittent? If it is intermittent, can I accuratley test it (i. e. it is working right now, so it would be correct)?

 

[Matt400]

A bad connection/connector could cause the intermittent but a sensor that is out of spec can also cause intermittent faults if it is borderline.

 

[turbinesurgun]

speed sensor

gotta agree with that my 99 did the same thing it was an auto and would not shift out of 1st gear

 

[motohead84]

I had a similar problem with the abs and brake light that wouldn't go out on my 01. After Paying $150 is diagnostic fees, and a $10 in parts , the problem was determined to be a bad brake switch, mounted just in above your foot in front of the brake pedal.



hope this helps

 

[pwerwagn]

OK, I took the sensor out and cleaned it off real good (a few guys emailed me and said it just usually gets dirty), and it still isnt working. I checked resistance and it was high (I think 1876 ohms). My moms 98 half ton 5. 9 is doing the same thing now, but her speedo still works. I am going to try swapping the sensors and see if it fixes either of our trucks. should botht trucks have the same sensor?

I will also check out the brake light switch.

thanks guys.

 

[Matt400]

I am going to try swapping the sensors and see if it fixes either of our trucks. should botht trucks have the same sensor?

I will also check out the brake light switch.

thanks guys.

My book shows it as the same part number. Brake light switches can cause the ABS lamp fault but haven't seen one of those cause a speedo fault.

 

[FourBarR]

had this problem ,replaced sensor, didnt help started to check wiring . these wires run along the outside of the left hand side of the frame. just where they make the turn towards the sensor, found wire harness chafed thru. check that area could be your problem. hope this helps.

 

[pwerwagn]

I actually was noticing the wiring looked a little frayed. I will check that too.