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ABS/speedometer/brake light


whywontitwork
08-20-2004, 02:37 PM
I'm having just about this problem on my 2000 dodge 1500 - and I'm hoping I can fix it without paying for an entire rear-end. My brake light is on, my ABS light is on, and my speedometer only works when I get to about 90 miles an hour....just kidding - works at around 70 mph - and only when I let off of the gas as the RPMs go down. I've never worked on a dodge much - but man...I'm seem to be getting alot of practice lately. I thought maybe since the speedometer was only working when I let off of the gas - that it was a Vaccume problem or some type of "back-pressure" problem. Did anyone figure out exactly what the problem is??? Is it the ABS sensor on the rear differential, is it something wrong with the differential itself, or does it have something to do with the brake system?? I replaced my front brake pads about a year ago - and one of my rotors was getting close - but how could that effect the speedometer - I dont think that the front brakes have anything to do with it. What would the rear brakes have to do with the speedometer?

Anyone know the solution to this problem???

-Jay

write off
08-20-2004, 04:50 PM
did you try replacing the speed sensor on top of the rear diff?

whywontitwork
08-20-2004, 04:56 PM
did you try replacing the speed sensor on top of the rear diff?
I am going to try and do that this weekend. - Have you every replaced one yourself? I actually haven't even climbed under there. How does is come off - does it unscrew - or snap out with some type of pin?

Thanks-

-Jay

write off
08-20-2004, 11:04 PM
It is right on top of the rearend. You need a 13 mill socket to get the nut of the stud and then the sensor itself is just pried out of the housing. There will be two wires running to it. Then just lube up the new one and then pop it into the carrier and put the nut back on. Mine had pretty much the same problem as you described. If you have a buddy with the same truck or spped sensor you could just try swappin with him to see if it cures you. No sense buyin one if it aint the prob. The sensor only takes about 10 min to replace

whywontitwork
08-22-2004, 07:23 PM
Man- I got under there on Satuday morning and that was pretty simple - I just pulled it out and cleaned it off to see if that would help - no help, so I called the dealer. They want $86 for the part - but I found it online with shipping for under $70. So, I put the part back in and I'll wait 'till it comes in UPS.
By the way, I pulled the part out - and it had some tiny metal fibers on it - is that a big deal?? Seems like that would just be from normal wear of metal gears working together.
How do you know so much about dodge trucks?

-Jay

BleedDodge
08-22-2004, 09:23 PM
Most of these sensors are located in the same place on all makes, not just Dodges.

Now you know how to change one, just in case you get a Chevy or something and the same thing happens.

As long as the fibers were small, then I wouldn't be worried. It's when you start seeing chunks of metal that you should raise an eyebrow...

whywontitwork
08-24-2004, 09:14 AM
Man - what a relief- its so nice when something works!!! The ABS sensor (rear differential speed sensor) was the problem. So I replaced it yesterday afternoon - very easily - and now everything works and all of my idot lights on the dash went out! The Kerrville Texas Mopar Dealership - (the only one) tried to charge me $85 for the part. So I looked it up on an online discount mopar dealer - for $68 including shipping. So I tried one more place - in Boerne, Tx - a big dealership supercenter - they sold it to me for $35....and they are open on Saturdays. They just made a long-term customer.

write off - and bleedDodge - thanks for your help!!!!

-Jay

bignoisey
09-01-2004, 11:21 PM
I'm having the same problem with my '99 Ram van. After reading this and other forum threads I'm convinced this is the problem. Last night I crawled under the beast, unplugged the ABS sensor and measured the electrical resistance. I've heard that it ought to measure around 1800-2400 ohms. Mine measured as an open circuit.
I tried to buy the sensor at Kragen, Auto Zone and NAPA today and nobody had what I think is the right part. Auto Zone had something they called a speed sensor, but it is a plastic unit with 1" threads that would screw into the differential housing for $12.95. I'm almost sure this is not the right part. If my information is correct the right part is held in by a stud and nut and just slides out (no threads) after you undo the nut. The only problem is I can't find it anywhere in an A/P store or on the net. My friendly Dodge dealership would gladly take $86 for an exact replacement, but I'd like to save a little in the process. Does anyone know where I can order an ABS speed sensor online? Can anyone verify what the electrical resistance should measure? My Hanes repair manual is not specific, but says the pre '92 sensor should measure under 2400 ohms.
Jay: If you read this can you help me find the web site you ordered from? Was your's threaded or did it slide out?

mxracer111
09-19-2004, 02:45 PM
i have the same problem, 1998 dodge ram 1500 2 wheel drive, speedo does not work from 0-30, (last week was 0-20) and abs, brake light is also on. mine also stalls everytime i come to a stop. did urs do the same thing

mprtech
09-19-2004, 02:58 PM
bignoisy the resistance should be 900 to 1400 ohms. OC is definitly bad. No it does not have threads.

er==EricH328
10-15-2004, 12:41 AM
Wow, I am surprised that this is such a common problem. I have a 1998 Ram. I am having the same problem with the dash lights and the speedometer. It appears that the sensor is a dealer only item and they want $70.00 for it. Can anyone tell me of a place that sells it cheaper? Thanks.

ral3ph
10-15-2004, 11:26 AM
Man- I got under there on Satuday morning and that was pretty simple - I just pulled it out and cleaned it off to see if that would help - no help, so I called the dealer. They want $86 for the part - but I found it online with shipping for under $70. So, I put the part back in and I'll wait 'till it comes in UPS.
By the way, I pulled the part out - and it had some tiny metal fibers on it - is that a big deal?? Seems like that would just be from normal wear of metal gears working together.
How do you know so much about dodge trucks?

-Jay

hey jay i cant get mine out as easy it seems it will move but won't come up at all did u pry on yours. and how dd you get the connector apart i can't figure it out.

thx for your help

whywontitwork
10-15-2004, 11:55 AM
Hey Ralph-
Its kindof tough to get up in there so that you can see what is going on - but there is a clip that holds the "connector" onto the sensor. the connector has a flexible plastic flap that snaps over a tiny ledge that is on the sensor. You just raise that flap with a flat-head screw driver and then pull on the connector. It should slide right off, but you might need to "wiggle" it back and forth as the flap is being "pryed" up. As for pulling the sensor out of the differential, It took me a few minutes to figure out where the sensor ended and where the differential began because it was such a tight fit. I thought maybe that there was a metal square form on the back of the differential that the sensor fit into. Well, thats not the case. That square form is about 1 inch by 2.5 inches with a bolt going through it, and it is the base of the sensor, and you have to pry underneath it. First, there is probably one single bolt that goes through a wiring harness, and then through the sensor, and it is threaded into the actual differential. Unbolt the bolt first, then you will probably have to pry on the sensor to get it out. I used a small pry bar or a flat head screw driver, and before I could get any leverage underneath the sensor, I had to tap the pry bar very slightly where the sensor meets the differential. This raised the sensor up just enough that I could begin prying it up just a little bit at a time. Be sure to pry a little bit at a time, working your way around the sensor so that it comes out nice an straight. To state the obvious -
Make sure that before you start - you try and clean all of the dirt and grime off around the sensor - because once you pull off the sensor - it's an open hole into your differential, and make sure you have the new part already to put it in - or you have access to another vehicle to make it to the shop- because you dont want to drive around with an open hole to collect dirt or loose oil in the back of your differential. If your just wanting to get a good look at it - before you buy a new part - (I did the same thing) just be careful when prying it out - not to damage it too much - it will still slide back in. Clean inside the opening of the hole with a clean rag just to get out any grime - then just line up the new sensor and slide it right in - it may take a very slight tap - but it should fit fine - be careful to make sure you get the wiring back in place as well as the rear brake line harness secured.
Good Luck - and I hope this helps!

-Jay

mxracer111
10-15-2004, 06:07 PM
i only paid 41 bucks including tax at my dealer here in NY

LTJGWorth
10-15-2004, 08:31 PM
Here's a big tip, take the spare tire down before trying this. It gives you about 5-6 inches worth of extra working room. In fact, i can sit underneath my truck with my head bent a little if i take down the spare tire.

Jalina
01-27-2008, 07:28 PM
:runaround: OK here is my deal. I had the same problem ABS,BRAKE,ENGINE and AIRBAG lights are all on plus SPEEDO, A/C and DEFROST don't work. I checked the voltage at the fuse box and I was getting 1.3v. Would it still be the REAR SPEED SENSOR? :frown:

rockwood84
03-09-2008, 03:24 AM
it is a dealer only part.

90sabre
04-16-2008, 10:40 AM
Wow, I am surprised that this is such a common problem. I have a 1998 Ram. I am having the same problem with the dash lights and the speedometer. It appears that the sensor is a dealer only item and they want $70.00 for it. Can anyone tell me of a place that sells it cheaper? Thanks.

Just did mine this weekend :)
I paid $53 at Advance Auto Parts(not sure if they are a fully national chain)

Leo
99 Ram 5.2 4X4

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