rockfoot

Was underneath the truck scoping out what I had to do to get the gas tank out when it occured to me that I have had a piece of tape over the light for the Anti-lock brakes on the "message board" on the dash board. This light came on soon after I bought the truck in 2000. I fooled with it a while and finally put tape over the amber light, thinking I would get to it later. Now is later. (I used tape instead of removing the light bulb so I would be reminded occassionally that it don't work) .... I did the diagnostic by grounding the wire on the control box and it told me -9 flashes- "high resistance to the speed sensor". I removed the speed sensor, cleaned it up real good, cleaned the contacts as best I could.... cleaned the female contacts on the end that was still under the truck, replaced the sensor and plugged it back in. Disconnected the battery for about a minute, then cranked her up.... same problem. I read out the sensor while I had it on the bench and the readings varied from about 10k ohms to 50k ohms... how much resistance constitutes "hi- resistance"?? That sounds "high" to me, but it does use reluctance and magnitism to trigger the control box... the ohmic value varied when I waved a wrench or piece of steel in front of the pickup... I also measured the distances from the exiter ring to the case surface and the length of the sensor... all good...Just curious if anyone else has chased this problem.

rockfoot

Installed new speed sensor in the differential and all is well. That was easy. All it took was money and a few minutes.....

wannadiesel

Glad you fixed it instead of disabling the system.

rockfoot

I wondered if that wasn't the trend when I didn't get any "posts" in reply. Normally, someone will chime in as "been there-done that"... Not this time.... so I figure there are a lot of light bulbs missing out there.

"B" SCARED

well i guess ill do mine now. just locked it up on the freeway and pitched it sideways trying not to hit someone.

rockfoot

Know the feeling... mine locked up on me when a lady pulled out in front of me. I was going about 65 on a 2 lane blacktop... I went out in the other lane sideways, scared to death.... reminded me of my old motorcycle racing days... all crossed up... Glad nobody got hurt...

rockfoot

by the way... for anyone that is interested, the new speed sensor read out at 1345 ohms.... (1.345Kohms) The old one that was bad read 44K to 50K ohms

Power Ram 250 C

So is this speed sensor located on the rear differential? Is it the thing that plugs into the top, front of the differential and runs up into the frame rail then converts into a plug with two wires coming out of it?

dodgenstein

Yup, that's it!!

flashgordon

Yup, My 4wd light work, now............ and that ABS or arwl lite, don't