Hi,

I have a 2003 Dodge Ram 1500 4x4 with the 5.7. Today we replaced my radiator as I noticed a leak in it. Well driving away, got about half a mile down the road and the ABS and BRAKE lights came on with the chime. I stopped and turned the truck off and back on again. A minute passes and they come on again.

Not long ago we replaced my drivers side hub which of course included a new ABS Sensor. I wiggled the wires for it and when I started the truck back up and put it in drive then came on and off and back on again randomly then stayed on. Each time the stay on I can feel the ABS kick in (or out?).

So take that with the fact that I have a P1501 code, I am wondering what the issue is or how I might be able to narrow it down?

 

1501 is speed sensor out of test range. You may need to find someone with a factory scan tool to tell you which on it is.

 

This situation is a lot like getting a UTI or the clap (not speaking from experience, just dabble in prevention ), you've got the symptoms and treatment is the same regardless of what is causing you the grief...

I don't believe it to be related to your radiator replacement, its just coincidence Its most likely a failure in the ABS/Speedo combined sensor on the top of the rear differential. Usually your first sign of trouble is if the speedometer looks to be notchy with speed & deceleration. First check to see if the harness has any mud or wetness that could cause a short or malfunction to the sensor, this includes the harness going to the general area of the speedo/abs sensor, it also includes checking the harness up to your trailer light connector, if corrosion is found clean corrosion if needed with WD-40 or PB Blaster or another electrical safe cleaner. The harness is pretty well protected through most of the chassis, so don't get bent up if you can't visually see the whole thing because its most likely fine, the most important parts to check & most likely to sustain failure are the connectors & abs sensor itself.


There is also 2 more harness connectors that connect the fuel pump, taillights, abs sensor & trailer light harness to the trucks main electrical systems that's located behind the drivers side front tire mud flap, its a place that mud (under the truck/behind wheel well) & moisture can also collect in, its a good idea to disconnect & inspect them as well...(caution on these...they'll rip your fingers up pulling them apart). Another less likely area to check for corrosion is under the battery/fuse box. Also just for piece of mind, visually check simple things like battery grounds, theres 2 main grounds near eachother, one that goes to the side of the drivers fender and another directly below that may be hidden that goes to the frame under the battery tray/fuse box. Its a great idea to check all these things first because they are simple to do and DO NOT COST ANY MONEY.

If it still throws a code you should replace the $25 rear abs/speed sensor. When you replace the abs/speedo sensor, take the cover off the differential and inspect the carriers tone ring for bad teeth as well as excessive metal shavings in the carrier housing, worn & pinnion gear teeth, spider gear wear and magnet for metal shavings at the bottom of diff. At this time it would be great to time your sensor change with your inspection of the inside of the differential & diff lube change incase the old sensor gets stuck in the diff and you need to pound it out, you'll already have the cover off and your differential will most likely need the lube change anyway, its a great idea and a expensive major component that often gets neglected on lube changes ;-) To preemptively answer your next question, the correct lube is 2 1/2 quarts of 80/90 gear lube. The Lucas stuff at Advanced already has the clutch friction modifier additive for limited slip rearends, read label to make sure it does just incase they sell a version I don't know about ;-) you'll know when its full when the diff cover weeps extra lube out. If on a budget and your truck doesn't have a limited slip and rather has a open diff just buy the Supertech Wal Mart 80/90 lube for $4 a pop.

Also check to see if your Emergency Brake was accidently depressed, even breathing on it will cause it to throw a brake light. Check brake fluid level as well.

The most expensive unit in the whole system and absolute worst case scenario (minus differential failure) is the ABS controller unit malfunctioning, but you most like have a rear diff abs/speedo sensor problem. This post is basically the whole abs system in a nutshell!


It sounds like a lot to do, but can easily be done in 2 hours and a 6 pack, and many of the things are near eachother.


**NOTE** Severe Differential Wear (more specifically tone ring damage such as rounded or chipped teeth & bad carrier bearings) can cause the ABS light to stay on indefinitely, which is why its important to check for wear and to listen for excessive hum out of your rear differential as to rule it out in your diagnosis.

 

Ha, thanks for the replies.

I do have an update though...

Those lights will ONLY come up when I turn past middle to the left. Even sitting still. Then go off when turned back to the right. So I am thinking that its one for the two front speed sensors?

 

Front ABS sensor wire is fatigued ;-)

You can replace the sensor or you can do what I did to my friends 2001 Durango if you don't have the cash...take the drivers side tire off and have a friend turn the wheel, see where the fatigue point is, splice new wires in its place and save $50.

 

Thanks for the tip. Yeah the drivers side we replaced the hub (sensor came with) and axle. Love winter storms. So I dont know if its that one but it could be. Is there an easy way to tell which side might be acting hateful?

 

If your truck is equipped with rear ABS only then it will be the drivers side front ABS sensor causing the problems. Even though a truck may have rear ABS only, it still takes a speed reference from the front drivers side wheel and it would be that sensor that is causing the brake light issue ;-)

 

Thanks for that information. Ill run out and take a look at that sensor in more detail.

 

Regardless of weather or not the truck has all wheel or rear wheel ABS, the effect of the sensor is instant (meaning no lingering dash light or diagnostic code), so if you take the front tires off and have a helper turn the wheel and see if when you grab the harness in a certain place if the light goes out or on, that is pretty much the easiest way to find out which sensor is causing the problem.


Hope this helps.

 

Thanks for the discussion. I was able to correct my problem with a wiggle test and cleaning the connection o the abs block. Once again, thanks.