Got this stupid bug. Every time i go around 40 miles an hour, my ABS and Brake light comes on! (note, my speed-O works perfectly) I restart the engine and the lights go off but comes back when traveling around 40 mph again. I know most people would say its the rear brake sensor thats mounted on the rear differential. So i have a 2001 dodge ram for parts and i took it off that truck.. Installed it and same thing.. Unpluged all my battery's for 12 hours hoping to reset the system and it still comes back...

Also i was driving and a car in front of me slammed on their brakes so i had to press hard on my brakes as well and noticed my wheels locked up pretty easily. What could be the issue? Could it be that both sensors are faulty and i just need to get a brand new one? I only have RW-ABS. Thanks

Wheel speed sensors on the front?? Those might be built into the hub. So be ready to spend some $$$.

Why dont know go and have the codes pulled. Worse case it's your ABS module, but more likely a speed sensor somewhere on the vehicle.

I went to a mechanic who's got a Snap On computer tester.. . He cleared my Check Engine light but said my truck cant communicate with his computer as my truck is a 1998 12v and is very limited on what he can do with the computer readings as everything is basic on that truck and lack electrical.

The Trucks computer wont allow him to get into the "ABS" part for any scanning. He said the Dealer can only access that. He still could but it would require some wires pulled and do individual wheel check which would take time. The Dealer wants $100 bucks just to connect to my computer.

Could it be that my rear differential sensor adjusted wrong? Does the sensor adjust at all? It seems like the sensor should adjust but when i tried it doesn't (of course i put little force because didn't want it to break). I herd of mechanics adjusting those things and one actually said might be that problem since abs and brake light comes on around 40mph.

Dodges ain't my thing, but if its like fords, take out the front sensors and clean the crap out of the hole and sensor ring.

Alex.

Just came back from NAPA. Had them check for codes while the lights where on. Here is what i got but both me and NAPA rep are a bit confused what this means. Maybe somebody might know?

P1594 Manufacturer Control / Vehicle SP / IDLE Speed Control AVX inputs

P1389 Manufacturer Control Ignition System OR Misfire



Is that good enough information to point out to a specific problem for a mechanic? Does look like it uh?

Wait.... isn't P1594 a VOLTAGE too high code? I do have my Dodge running an OUTSIDE Mopar circuit regulator from 80's dodge because my computer fails to turn on my alternator so i had to rewire it. I tested my truck while running and i am getting a reading between 14.85 to 15.15 volts. Too high still? Some say its good. On the Gauge its with-in "normal" range but almost boarder line.

Whats the proper IDL RPM? My IDL is around 900 rpm. Is that too high? I think i go like 10mph in second gear IDLING


Come to think of it, my voltage regulator is running around 14.80 to 15.10 volts, ...Could that be caused by a high IDL? and if indeed that is high voltage due to high rpm, could that be the reason my p1594 Code?

The ABS light and brake light are most likely caused by the rear axle speed sensor...dodge uses two sensors: one in the rear axle, and one in between the tcase and trans. I had this same thing happen in my 99 2500 and 94 1500.

Replace the sensor in the rear axle (top of the center chunk), and your ABS and brake light issue will probably go away.

I went to a mechanic who's got a Snap On computer tester.. . He cleared my Check Engine light but said my truck cant communicate with his computer as my truck is a 1998 12v and is very limited on what he can do with the computer readings as everything is basic on that truck and lack electrical.

The Trucks computer wont allow him to get into the "ABS" part for any scanning. He said the Dealer can only access that. He still could but it would require some wires pulled and do individual wheel check which would take time. The Dealer wants $100 bucks just to connect to my computer.

Could it be that my rear differential sensor adjusted wrong? Does the sensor adjust at all? It seems like the sensor should adjust but when i tried it doesn't (of course i put little force because didn't want it to break). I herd of mechanics adjusting those things and one actually said might be that problem since abs and brake light comes on around 40mph.


There's no adjustment on the sensors. They are just drop in. It could be possible the sensor is a different part number between the years.

check this problem on the TDR that is turbo diesel register. Just ask the question.

Just came back from NAPA. Had them check for codes while the lights where on. Here is what i got but both me and NAPA rep are a bit confused what this means. Maybe somebody might know?

P1594 Manufacturer Control / Vehicle SP / IDLE Speed Control AVX inputs

P1389 Manufacturer Control Ignition System OR Misfire



Is that good enough information to point out to a specific problem for a mechanic? Does look like it uh?


P1594 says the charging system voltage is too high
P1389 says there is no ASD voltage present at the pcm

Niether one has anything to do with your abs light.
When you changed out the rear speed sensor with the spare/used one, did you happen to notice how shitty the gear oil looked? How many years has it been since you pulled the cover?
Its possible that the tone wheel is fawked up, or there is so much metal dust in the gear oil that it is throwing off the sensor...not likely, but possible.

Or you could just go to the dealer, and pay them...that way its fixed right the first time;)

The ABS light and brake light are most likely caused by the rear axle speed sensor...dodge uses two sensors: one in the rear axle, and one in between the tcase and trans. I had this same thing happen in my 99 2500 and 94 1500.

Replace the sensor in the rear axle (top of the center chunk), and your ABS and brake light issue will probably go away.

So your saying my 2001 ABS sensor might be fault too?


check this problem on the TDR that is turbo diesel register. Just ask the question.

What does that mean? I do have a HY35 turbo in their instead of HX35W because my HX35W was shot.

Go to the TDR site which only deals with dodge diesel trucks and ask or tell about the problem and someone will tell you how to fix it.

Go to www.cumminsforum.com that is a Dodge Cummins site and they won't harrass you and run you off like TDR. The guys on cumminsforum know there stuff. You can even find good deals on parts over there.

It doesn't matter what website he goes to, all they can do is guess, and tell him to throw parts at it until he gets the abs codes pulled;)

Today i notice my "Cruse Control doesn't work" Light comes up but doesn't hold speed. Also my Gauge and headlights flicker back and forth little bit if. What could it be? Bad computer causing all these issues?

I bet a mechanic could narrow it down to a sensor or connection now that theirs cruse control involved with the issue.

Really dumb question, but have you checked the brake lights when all this is going on? Do they work? Are they stuck on? Is any of the wiring for the brake light switch modified for a brake controller or the like?

If the brake light switch is sticking, than after awhile the abs light and the red brake warning like will come on, cause they sense a problem, this will also make the cruise inop, cause it thinks you are riding the brakes;)

Had the same problem! did you check the ABS switch under the battery or the vaccum switch mounted by the firewall, vaccum leaks loose wires dirty wires,flush out brake system and add new fluid, how is your fluid level? check rear wheel sensors and the one on the rear Diff, try a new one!:D

The ABS light and brake light are most likely caused by the rear axle speed sensor...dodge uses two sensors: one in the rear axle, and one in between the tcase and trans. I had this same thing happen in my 99 2500 and 94 1500.

Replace the sensor in the rear axle (top of the center chunk), and your ABS and brake light issue will probably go away.

So your saying my 2001 ABS sensor might be fault too?




From 1994 through 2002 (in the 2500/3500) they used a very similar braking system...individual sensors on the front wheels (when equipped with four wheel ABS) and a sensor for the rear wheels.

There are two speed sensors, the ABS sensor in the rear diff also functions as a low speed speed sensor, and that is the reason your speedo suddenly "works" after 40mph...it switches from the rear axle sensor and begins to read from the speed sensor in the trans.

However, it sounds like you may have multiple problems...cruise control vacuum controller, electrical, and the ABSs...

He stated in the first post that the speedo works properly. And if the rear sensor was bad, it would only effect the speedo til 15 mph, not 40;)

He stated in the first post that the speedo works properly. And if the rear sensor was bad, it would only effect the speedo til 15 mph, not 40;)


All three of my trucks were between 30 and 40mph?? And it was the rear ABS sensor every time. The speedo worked properly as long as I was above those speeds...drop below that speed (30 t0 40mph) and the speedo dropped to zero.

I think he has multiple issues, not one.

On edit, I see he clarified the part about the speedo...but I agree that it sounds like an ABS issue.

Did some testing today... took it to a different mechanic. The Mechanic did a computer test and said that i am "not getting any voltage to my rear differential sensor"

I told him, how is that possible? My speedo wouldn't be working until like 25-30 miles if at all......... and he said "my speedo works off my transmission speed sensor and my rear differential sensor is ONLY ABS sensor."

So i paid him $33 dollars for the scan test and on my way i went home to do some testing.... Got home, un-pluged my clip from the rear sensor and put my volt meter in the 2 pin slot. Turn the ignition on and i got a reading of "4.85 volts" . So then i kept it unpluged and fire the truck up.. I decided to take it for a spin around the neighborhood. Turns out my Speedo did NOT WORK AT ALL WHEN UNPLUGGED FROM REAR SENSOR. So obviously the mechanic didn't know what he was talking about and i am getting power to my sensor. Once i plugged it in, my speedo is working again.

so WTF. Kept looking around. I notice the 4 "air vacuum lines" located on the transmission and goes up to the engine area. (the green line goes to no-where, it just has a funny clip in the end.) That has nothing to do with ABS does it? I started the truck and put my figure on my green line and seems it has no push nor suction.

...... back to step one. WTF is going with this truck LOL>

bring it to a chrysler dealer ship we use a factory scan tool called the DRB III. It will pull the codes from the ABS module not the ECM like everyone else is/has. Once you get the codes from the ABS module you can make a diagnosis.

Did some testing with my mulitmeter today. Found out my 2 pin clip that plugs into some kind of sensor way on top of the transmission isnt getting any voltage through those wires.

I even started the truck and still no voltage running through those wires. So that question is, what kind of sensor is that's mounted way on top of my manual transmission which has barely enough room to stick your hand their? ? I probably cant even remove that clip, it seems like its bolted? Cant see.

Other question is, the 2 wires / pin / clip SHOULD carry either 5 volts (like the rear sensor) or 12 volts (like the front axle sensor? Or no voltage?


Test i did.

1.unplugged rear Def sensor, speedo doesn't work..... proof that the sensor works. Also getting around 4.80 volts in the clip.

2. Tested front axle sensor. Getting 12 volts in that pin. (didnt try driving while unplug) Set my volt meter to 20 ohms and geting a "0" reading on the sensor. Is this right way to check for continuity?

3. Found some kind of sensor on top of transmission. Tested the 2 wire pin/ clip. No voltage comming... Its the same looking clip/pin like in front axle sensor. Front gets 12volts rear def sensor gets 4.80

4.Unplugged my Brake sensor switch. Played around with that a little bit while driving and other test, all seems good. (does click here and there sometimes.)


Any help thanks. 12v 5.9 3500 4x4 manual.

What sensors are you talking about?? Top of the tranny?? Is it the back up light switch?

Front axle, you mean the disconnect servo??

Niether one have anything to do with the abs...

Did you check the brake lights yet?

How about the junction connector under the hood in the PDC? I don't remember what year they started using them, but there is a 10mm bolt that holds down a plug in the PDC, if you have one, take it off, and check for water intrusion.

If none of that shows up, take it to a damn dealer:flipoff2:
If you lived close, I would already have come over and fixed it, just so you stopped beating your head against the wall:p

From what i know, there are 2 abs sensors on a 98 dodge ram 3500 4x4 manual. One on rear DEF and other on transmission. Ive heard theirs one on front axle if you have the 4x4. Thats why i checked their.

The one on transmission has i think (green and purple) wires. I will double check that...... Also it is located about "center" of transmission but on the very top of it. Its hard to stick your hand up there at times. But its there. I can take a picture.

As for dealer, i think i will pass on the dealership. Its a freaking 12valve system it shouldn't be this hard yet at times it really can be with no computer support. The Dealer will be stuck just as i am . Its not a 2000 or newer models where you can just plug in the computer and it will tell you what sensor or whats wrong with the ABS. I don't want to take it to dealer because i know that little 18 year old boy is not gonna figure out my problem. There gonna say "bad ABS module" ... "Need to change rotors and brake disc" "Need to change sensor" ..... I am gonna waste my $100 just on worthless diagnostics that aint gonna say jack about ABS. There going to throw their ideas at me and im gonna keep coughing up money. I read horror story's online of people spending $1,500+ dollars on these ABS problems at the dealership replacing one part after another. I even read one story a guy took his in, paid $300 dollars to get his rotors and brakes changed problem remained... went to another recommended dealer and they charged him another $300 dollars to do the same job again because they said wrong brakes. They replaced ABS module and so forth..... Also on top of that is the economy. I dont want to spend but the dealership needs money as they are suffering, im sure if they know the problem they will add a few extra items to change just cuz and call it the same problem.


I respect everyone's opinions and open mind discussion and thanks for the helping hand. I will keep digging and find the issue... So far i fixed my voltage meter issue and spent about $33 bucks on this ABS. I will keep you up to date when i find the issue.

Why are people so dumb??

If I took my truck to a dealer, and said "My abs light is on, please fix it."
They would say "Diag starts at 1 hour, or $125." You then say okay.
They call you back after awhile, and say "you need a rear wheel speed sensor, its gonna be $300 parts and labor, including diag" Then you say, "are you sure thats the problem?" They say "of course"

And if it doesn't fix it.......DON'T FAWKIN PAY FOR IT!!!!!!!!!!!!!!!

If they call back and say, yep, we replaced that, and found there was another thing, its gonna be $500 more.....don't take you truck somewhere else.....tell them to remove the parts that didn't fix it, and replace the parts that will, or leave all the parts, and only pay for the ones that fixed it:shaking:


Its not that hard. Or you can keep beating your head against the wall. Your choice;)

Thats how i handle business. However if you've been to the dealer lately you are well aware that they don't operate like that any more. Everything is prepaid up front now. INCLUDING ORDER PARTS!! And there return on parts polices has changed also. You cant return part even if you never opened it! Once you walk out the door its yours. You can only EXCHANGE parts if they are faulty.

So if they say its bad sensor and you want them to change it, once its change you already prepaid for it..... Now for me to test it i would need to go 40 + miles.

Trust me i get my every penny count when i spend it on things like. I push until i get results. Unfortunately in my case and with the new policy at the dealership i would be trap. I learned that the hard way buying a part i found an alternative for few weeks back. I prepaid for the part so even if i didn't pick it up and have it sit at the dealership i still would have no refund. so i just got the part.

----------------

If only someone could tell me what that sensor is and how much voltage its suppose to receive the one top of transmission, i would get this issue resolved. I know my problem is either this sensor on top of tranny or brake switch clip. Actually it might be a REVERSE light that's on top of the tranny, would have to confirm. Those are the two biggest possibilities if it turns out its not a reverse light.

checked for reverse lights today, was told they don't work...... so almost certain now that on top of the tranny is a reverse light sensor and its getting no power to their.. Gonna put it in reverse and run my multimeter to see if i get voltage that way. If i do, bad sensor, if i dont bad wireing.

checked the fuses, found a blown fuse for "back up light 15amp" .. replaced it now reverse works and getting 12 volts power to the 2 wire pin clip which confirms its a "reverse sensor" on top of tranny.

Must of blown the fuse when i disconnected and took the truck for a test run.

Well FIXED IT!!!! Save hundreds of dollars if not thousands by avoiding the dealership. Guarantee the dealership computer would not have located this problem because even 3 mechanics couldn't figure it out. Turns out, has nothing to do with ABS sensors or ABS although the problem conflicts both Brake light and ABS light. The problem was a FAULTY BRAKE SWITCH by the brake peddle! I decided to replace that since all the sensors check out working condition. $10.99 at Cost less auto and problem Fixed!

I guess what happens is the computer trys to check the brake switch when traveling 35 to 45 miles to make sure your not pressing your brakes while driving. If switch is bad, the ABS and BRAKE light comes on. This is only when you SPEEDO works perfect! If you have a faulty speedo 25 mph and under, its the rear DEF switch. Also this fixed my CRUISE CONTROL! Works Great!!!

= What we've learned. ABS light on and brake on light when going 40 mph and speedo works great = bad brake sensor (if all wireing are in great shape and getting correct connection)

You think thats bad, I had a dinging going off in my 2004 dodge 3500 and I couldn't find the problem and it was driving me nuts. It was the tail light burnt out warning alarm, WTF.

i know LOL sometimes the way they wire the vehicle makes you stop and think for a second. Is the purpose of all this to confuse the individual and force them to come into dealership and cough up major doe? Such a scam. :shaking:

The problem was a FAULTY BRAKE SWITCH by the brake peddle! I decided to replace that since all the sensors check out working condition. $10.99 at Cost less auto and problem Fixed!
Also this fixed my CRUISE CONTROL! Works Great!!!



Wow, thats amazing, what made you think to check the brake light switch??

Really dumb question, but have you checked the brake lights when all this is going on? Do they work? Are they stuck on? Is any of the wiring for the brake light switch modified for a brake controller or the like?

If the brake light switch is sticking, than after awhile the abs light and the red brake warning like will come on, cause they sense a problem, this will also make the cruise inop, cause it thinks you are riding the brakes;)

Why i never changed my brake switch earlier because my brake lights and everything else on the truck worked perfect! No need to replace the brake switch as it DIDN'T show any signs of bad brake switch. Every time i press the brakes ALL lights WORKED! Happy? :shaking:

The only other issue that i had with the truck was voltage regulator which i had to wire in an exterior retaliatory to correct that problem.

Now, what MADE me change my brake switch EVEN THOUGH MY BRAKE LIGHTS WORKED FLAWLESS was because i was 100% sure my REAR DEF switch was working properly. Once i confirmed there was no second ABS sensor on the transmission i decided to start spending money as it was my only option left. The first thing i bought was the BRAKE switch because that's what sends a signal to ABS module when you are currently DRIVING. If i had ABS issue, it would have pop up from the point i started the truck or at least with in 40 miles per hour. Beside, i know that the next quickest sensor to fail in a braking or abs system is the brake switch as it all copper pins in their that can get bent up and wore down over time and not to mention is spring loaded which springs alone don't last long under pressure. That brake switch moves parts around every time you push and release the brake.

Like i said, if i took it to dealership i would have probably ended up with new rotors, brake pads, and a $400 ABS module and maybe some other parts replaced before they would look at the brake switch.

Sounds like you know it all...sorry to get in your way:shaking:

Yes too high! 650-700rpm

Whats the proper IDL RPM? My IDL is around 900 rpm. Is that too high? I think i go like 10mph in second gear IDLING


Come to think of it, my voltage regulator is running around 14.80 to 15.10 volts, ...Could that be caused by a high IDL? and if indeed that is high voltage due to high rpm, could that be the reason my p1594 Code?