2nd Gen Non-Engine/Transmission Abs,speedo,red Brake

[DavidC]

Just picked up the truck at Cummins Phoenix 11/19/04 minus the 53 block and a 56 is in it's place. The last thing they did was steam clean the engine. I have an ABS and Red Brake light on the dash illuminated. The speedometer will not work until first gear reaches 1800 rpm or it shifts to second. When decelerating once it downshifts to first the speedometer goes dead. All of this leads to the speed sensor in the rear differential except the red brake light. The only thing I find in common with everything is the ABS controller. I unplugged the Emerg. brake switch with no change,ohmed the pressure switch which if activated goes to ground and it shows open. Unplugged the ABS controller and lost the red brake light but the ABS stayed on. On a 99 the speed sensor goes directly to the ABS controller which if bad could be the speedo problem although not working until 1800 rpm or the shift to second has me puzzled. Checked the continuous voltage to ABS controller ok. Checked the engine run 12V to controller ok. Checked both grounds ok. It looks like I need a new controller for 142. 80 at Tenafly Chrysler Jeep. All the associated parts of this system are dry and no resisdual water found anywhere. Checked for codes with the laptop and OBD-2 software and came up dry. Anybody have any other ideas



Dave

 

[JSykes]

It sounds like the rear wheel speed sensor to me. Grab your multi-meter and check the resistance of the RW speed sensor. It should read around 1800 ohms if it is good. If it is considerably less than that, change the sensor. The sensor is a lot easier and cheaper (around $40) to replace than the abs controller. The RWSS is a very, very common item to go out (even on the 1/2 tons).



Jay

 

[DavidC]

Seems odd that everything worked when I dropped it off at Cummins. When I started it to leave a week later I have this. I will check the resistance. What really bothers me is they said the shortblock came without a tone wheel on the crankshaft for the cps. This was after they installed the engine . The service guy said they could install some jumpers to get around this problem but decided to pull the engine again and do it right. Could they have jumpered around something initially that caused this?



Thanks

Dave

 

[JSykes]

I doubt that Cummins did anything to cause it. Mine went out this time last year. I had my truck down for about a week doing a repair on some leaking transfer case seals. Got it all back together and backed it out of the garage and the ABS & Brake lights were on. Like your situation, everything was fine before I started working on it. Replaced the RWSS and it took care of the problems.



Jay

 

[LHartman]

It sounds like the rear wheel speed sensor to me. Grab your multi-meter and check the resistance of the RW speed sensor. It should read around 1800 ohms if it is good. If it is considerably less than that, change the sensor. The sensor is a lot easier and cheaper (around $40) to replace than the abs controller. The RWSS is a very, very common item to go out (even on the 1/2 tons).



Jay

I'd put my $$ on this. I had the exact symptoms with mine and it was the RWSS. Easy fix. Five to ten minute job.

 

[DavidC]

Looks like you guy's are right. Ohmed sensor, reads open. Auto zone said they have 2 in stock and showed me the part they have. Not even close. Even the website shows the wrong part. Guess I will check with local dealer tomorrow. Can anyone tell me how the speedo could possibly consistantly work at 1800 or higher RPM.



Dave

 

[JSykes]

If I remember correctly, on 98 and newer trucks with 4 wheel ABS there are speed sensors in the front and rear axles. The rear wheel speed sensor is the primary vehicle speed sensor for the speedometer. The front speed sensor will take over this duty if there is a RWSS code set. So, what you are seeing is not RPM related but MPH related (usually around 20 mph the speedo with register).



Hope this helps explain it.



Jay

 

[RKraiza]

I was reading your post and have to disagee with you with regards to Cummins causeing a problem. In my opinion, Cummins is becoming one sloppy, unknowledgable orginazation. Don't beleive me, read my post under "engine miss". Theve cost me around 6 grand without fixing the problem I have.

 

[DavidC]

Problem solved. Installed new speed sensor at rear differential. Everything works again.

Thanks for the help



Dave