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Dealer Techs , ABS light on a 98 ram 2500 #3020031
03/01/22 04:55 PM
03/01/22 04:55 PM
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JohnRR Offline OP
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I just got a new 2 me 98 2500 Cummins Ram , RWD. The ABS light on the dash is flashing, only the ABS light . Everything I read on line say the ABS light and the brake light flash together , mine does not . It has code 37 according to the Ford dealer that I bought it from. Code 37 doing an online search is for the rear axle mounted speed sensor, it's a cheap enough part to replace.

I've also read that if the underhood CAB is replaced it needs to be reset with a DRBIII tool , is this the case ?

Thanks


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020044
03/01/22 05:35 PM
03/01/22 05:35 PM
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That's the way our '98 acts. When it gets really cold (-10 or colder) the ABS light comes on. Same code, rear differential sensor. Warms up, goes away.


"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: 6PakBee] #3020060
03/01/22 06:28 PM
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90 percent of the time its the wiring going to the sensor that breaks down, You can ohm the sensor out to prove it. Birdtracker

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: 6PakBee] #3020096
03/01/22 09:15 PM
03/01/22 09:15 PM
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Originally Posted by 6PakBee
That's the way our '98 acts. When it gets really cold (-10 or colder) the ABS light comes on. Same code, rear differential sensor. Warms up, goes away.


Similar on my 96. When sensor was cold, would fail on startup. Warm would work. Sensor is an easy fix. Old one was stuck in there pretty good. Blow off the dirt and debris before you pull off to prevent junk from falling in.

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020102
03/01/22 09:33 PM
03/01/22 09:33 PM
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John two common items are the sensor and the other is the wiring, Common area up along the frame where the harness can flex with the suspension extending.

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: NITROUSN] #3020162
03/02/22 10:33 AM
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Thanks guys , I'm going to get it up on a lift at lunch so I can get a good look at the wiring .

The odd thing I notice is the ABS light is flashing all the time once the dash self check is finished, whether the engine is running or not , moving or not , no brake warning light . I have no history on what's been done to the truck , bought it on line 1600 miles from where I live so this should be interesting.


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020248
03/02/22 03:04 PM
03/02/22 03:04 PM
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A12 Offline
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Originally Posted by JohnRR
I just got a new 2 me 98 2500 Cummins Ram , RWD. The ABS light on the dash is flashing, only the ABS light . Everything I read on line say the ABS light and the brake light flash together , mine does not . It has code 37 according to the Ford dealer that I bought it from. Code 37 doing an online search is for the rear axle mounted speed sensor, it's a cheap enough part to replace.

I've also read that if the underhood CAB is replaced it needs to be reset with a DRBIII tool , is this the case ?

Thanks


John, sans an OBD scanner a lot of Chrysler products can be self-scanned with the key on/off cycle like in this video. Some models will display the codes and some earlier models used the "blink" codes for self-diagnostics. Most local auto parts stores will clear the codes or reset the OBD for you no charge. The self-scan key on/off method just helps as a quick check to see if what's going on. Hope this works for your RAM and hope it helps.


Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: A12] #3020260
03/02/22 04:17 PM
03/02/22 04:17 PM
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JohnRR Offline OP
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Originally Posted by A12
Originally Posted by JohnRR
I just got a new 2 me 98 2500 Cummins Ram , RWD. The ABS light on the dash is flashing, only the ABS light . Everything I read on line say the ABS light and the brake light flash together , mine does not . It has code 37 according to the Ford dealer that I bought it from. Code 37 doing an online search is for the rear axle mounted speed sensor, it's a cheap enough part to replace.

I've also read that if the underhood CAB is replaced it needs to be reset with a DRBIII tool , is this the case ?

Thanks


John, sans an OBD scanner a lot of Chrysler products can be self-scanned with the key on/off cycle like in this video. Some models will display the codes and some earlier models used the "blink" codes for self-diagnostics. Most local auto parts stores will clear the codes or reset the OBD for you no charge. The self-scan key on/off method just helps as a quick check to see if what's going on. Hope this works for your RAM and hope it helps.



I tried that expecting a code in the odometer window and there was none. I didn't pay attention to the CEL light, which was how one of my older rams spit out a code... I'll give that a shot . When I put an Actron scanner on it no codes were present ?


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020261
03/02/22 04:23 PM
03/02/22 04:23 PM
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Colleyville
3hundred Offline
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Originally Posted by JohnRR
Originally Posted by A12
Originally Posted by JohnRR
I just got a new 2 me 98 2500 Cummins Ram , RWD. The ABS light on the dash is flashing, only the ABS light . Everything I read on line say the ABS light and the brake light flash together , mine does not . It has code 37 according to the Ford dealer that I bought it from. Code 37 doing an online search is for the rear axle mounted speed sensor, it's a cheap enough part to replace.

I've also read that if the underhood CAB is replaced it needs to be reset with a DRBIII tool , is this the case ?

Thanks


John, sans an OBD scanner a lot of Chrysler products can be self-scanned with the key on/off cycle like in this video. Some models will display the codes and some earlier models used the "blink" codes for self-diagnostics. Most local auto parts stores will clear the codes or reset the OBD for you no charge. The self-scan key on/off method just helps as a quick check to see if what's going on. Hope this works for your RAM and hope it helps.



I tried that expecting a code in the odometer window and there was none. I didn't pay attention to the CEL light, which was how one of my older rams spit out a code... I'll give that a shot . When I put an Actron scanner on it no codes were present ?


As I recall, ABS in these years is a completely separate system, specialized equipment is required to diagnose them. Rear axle sensors were first used in 1998.


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: 3hundred] #3020285
03/02/22 06:33 PM
03/02/22 06:33 PM
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Not sure on a 98 but my on 01 I can hold down the odometer trip button then turn ignition on then release button and dash will self check and codes will show in the odometer place.

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: cudaman1969] #3020405
03/03/22 07:34 AM
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To get ABS codes you have to ground out on of the pins on the OSD2 connector. The ABS light will flash and give you the code/s. Don't know what pin or the flash count you have to look in the factor service manual for that.

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: Moparite] #3020453
03/03/22 11:33 AM
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JohnRR Offline OP
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I crawled under the truck and see that the sensor has been replaced, I ohmed it and it is not open so I'm guessing that a wire is broken somewhere ?

Looking under the hood where the CAB is for the RWAL system there is a connector that is not connected to anything and there is nothing not connected on the control board. I really need to find a wiring diagram for this thing .


running up my post count some more .
Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020578
03/03/22 07:11 PM
03/03/22 07:11 PM
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Mentor, OH
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You can download the FSM here. Handy if you have a tablet to take out to the garage.

https://www.ramforumz.com/threads/all-2nd-gen-service-manuals-in-pdf.234888/

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: doggs330] #3020618
03/03/22 10:02 PM
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JohnRR Offline OP
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Originally Posted by doggs330
You can download the FSM here. Handy if you have a tablet to take out to the garage.

https://www.ramforumz.com/threads/all-2nd-gen-service-manuals-in-pdf.234888/


Thanks , I found the FSM online , downloaded the schematic and pages on RWAL, the extra connector is for trucks with 4 wheel ABS.

I was able to test the rear sensor up to the controller under the hood and I have continuity and the same reading I had under the truck. I also checked the grounds and supply voltages and all are present. Just need to pull the code , but I think it's the control head that is the issue ?

I was also given the idea to check the sensor with an non digital ohm meter , spin the rear axle and see if the needle sweeps up and down?

I'm noticing that the peddle does pulse when I stop, so something is going on.

I could just bypass it and pull the bulb but I really want to fix it .


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020622
03/03/22 10:10 PM
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Get the codes pulled. It could be a problem in one front circuit. The code should help narrow it down.

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: NITROUSN] #3020625
03/03/22 10:18 PM
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JohnRR Offline OP
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Originally Posted by NITROUSN
Get the codes pulled. It could be a problem in one front circuit. The code should help narrow it down.


It's rear wheel only ABS , tomorrow I'm going ground pin 13 on the ODBII connector and read the number of times the light flashes.

I wish I had access to a DRB scan tool.


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020629
03/03/22 10:29 PM
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Originally Posted by JohnRR
I crawled under the truck and see that the sensor has been replaced, I ohmed it and it is not open so I'm guessing that a wire is broken somewhere ?

Looking under the hood where the CAB is for the RWAL system there is a connector that is not connected to anything and there is nothing not connected on the control board. I really need to find a wiring diagram for this thing .


Pull that sensor out and take a peek. It's a magnet so any metal floating around in the rear will collect on it and cause errant signals. Missing/chipped/broken teeth on the trigger wheel will cause the same. Graph or lab scope will show that stuff as well. Good luck...hope it's an easy fix!

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3020992
03/05/22 09:07 AM
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JohnRR Offline OP
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Originally Posted by JohnRR
Originally Posted by NITROUSN
Get the codes pulled. It could be a problem in one front circuit. The code should help narrow it down.


It's rear wheel only ABS , tomorrow I'm going ground pin 13 on the ODBII connector and read the number of times the light flashes.

I wish I had access to a DRB scan tool.


Last night I picked up an Innova scanner that could see the ABS codes . I have 4 ,

37 , erratic rear sensor signal

47 shorted iso solenoid or open ecu output, LF

45 open iso solenoid or shorted ecu output, LF

65 open power relay contacts

I can't find anything in my 2000 FSM that mentions anything about these codes ? Google here I come .


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Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: JohnRR] #3021002
03/05/22 10:20 AM
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if i recall, those codes usually show up when antilock ecu is bad. again if i recall those ecu's are not avail new or from dealer. usually a bone yard and it is a crap shoot getting a good one. might be differeny now but that was how it used to be.

Re: Dealer Techs , ABS light on a 98 ram 2500 [Re: trw1982] #3021017
03/05/22 11:53 AM
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If you end up needing a ecu for the antilock brakes check ebay. I seen some on there recently.

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