Problem with abs

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
Good evening guys, I have a problem with the abs of my Dodge Ram.
In practice, when I turn on the car (by pressing the brake pedal) the ABS and parking brake light are off but when I release the brake pedal the lights come on.
The ABS sensors (front L and R, rear differential) are ok.
The Brake light switch are ok.
can someone help me?
Thank you all :)
 

Rustycowl69

Senior Member
Joined
Oct 24, 2015
Posts
857
Reaction score
171
Ram Year
2001 ram 3500
Engine
V10
have you checked the brake fluid reservoir? i's there air in the lines?
 
OP
OP
R

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
hi to all guys today I changed the brake fluid but the abs light is always on just release the brake pedal when stationary.
i checked the brake light switch in the brake pedal:
when i press the brake pedal:
pins 1 and 2 continue
pins 3 and 4 does not continue
Pins 5 and 6 does not continue
Brake pedal released
pins 1 and 2 does not continue
pins 3 and 4 continue
Pins 5 and 6 continue
Pin 1 corresponds to the Brake Switch Sense
pin 2 corresponds to the ground
pin 3 corresponds to the speed control supply
pin 4 corresponds to the speed control brake output switches
pin 5 corresponds to the output brake lamp switch
pin 6 corresponds to the fused b (+)
-----making a bridge between the pins 5 and 6 the abs light comes on.
can someone help me? thank you so much
 

DodgeTx

Senior Member
Joined
Apr 29, 2015
Posts
899
Reaction score
244
Location
SEGUIN
Ram Year
2001
Engine
5.9L Cummins, 5.2l v8
Unfortunately, ABS is a bit tricky without a shop. I currently have abs and brake light on, have replaced all speed sensors, and brake switch on pedal. Doesn't affect drivability but is annoying to see on the dash.
 
OP
OP
R

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
Guys today I took the continuity test of the abs pump connector (2 ways, red and black) and there is continuity between red and black..the pump is dead?
20170103_155107.jpg
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
First, the pump motor is nothing but a long copper winding, it would be a problem if there were no continuity. The pump motor is likely working just fine.

My question is, do your brake lights work?

Unless the wiring diagram in the service manual is wrong (it very well could be).

When you depress the brake pedal, pins 1 and 2, and pins 5 and 6 should show continuity, pins 3 and 4 should show open. The reverse should be true when the brake pedal is released.

For testing purposes, when you are testing the switch out of its mount, when the switch plunger is pushed in, the brake pedal is released. When the plunger is let out, the brake pedal is depressed.

Pins 5 and 6 simply power the brake lights, there is no sensing going on for these two pins.

Pins 3 and 4 control the speed control circuit, if your cruise control works, these pins work properly.

Pins 1 and 2 are the brake switch sense, this input goes to the PCM.


If your brake and ABS light comes on only with the brake pedal being released, i'd really need to see the codes stored. Unfortunately, I think the ABS codes can only be read with an MDS or DRB scan tool.

I can take a guess and say that something is failing the power on self test.

In practice, when I turn on the car (by pressing the brake pedal) the ABS and parking brake light are off but when I release the brake pedal the lights come on.

I'm not following what you're saying. Are you holding the brake pedal when starting the vehicle? That isn't necessary in a vehicle as old as yours. If so, don't and see if the problem persists.
 
OP
OP
R

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
unfortunately there is no dodge dealer in my area, the nearest is 1300 km from me.
according to the manual this is the impedance of the front and rear sensors
Front sensor:
90 ° C (194 ° F) from 2259 to 2761 Ohms
25 ° C (77 ° F) from 1800 to 2200 Ohms
-40 ° C (-40 ° F) from 1332 to 1628 Ohms
Rear sensor:
90 ° C (194 ° F) 2900-3500 Ohms
25 ° C (77 ° F) from 1600 to 2300 Ohms
-40 ° C (-40 ° F) from 1000 to 1400 Ohms

I have 1066 and 1020 ohms in front sensors and 1880 ohms in the rear sensor (new last month) could be the front sensors?
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Its possible, but I cannot find the spec for that in the factory service manual. What i'd do, is take it somewhere with low traction, and slam the brakes to see if the fronts lockup. If they do, its very possible that the fronts are bad.

However, the ABS sensors are simply copper wire wrapped around an iron core. What that test is supposed to detect is whether or not the sensor has shorted or become open. I'm not so sure about the RAM sensors, but most GM sensors are considered good if they fall within 800-1800ohms. What I would do is check the sensors themselves and make sure they are clean and free of damage.

Where you measured will also have an impact, you should measure as close to the ABS module as possible as the wire leading up to it will add to the resistance.
 
OP
OP
R

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
I checked the front sensor in the wheels and are perfect.
I measured the front sensors resistance in the ABS control module connector.
the ABS and parking lights come on just release the brake pedal,
exactly when the pins 5 and 6 are combined.
PIN 5 Brake lamp switch output
PIN 6 Fused B(+)
Cattura.jpg
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Pins 5 and 6 should make contact only when the pedal is depressed, when the plunger is allowed to extend. When the pedal is allowed to return to its resting position, and the plunger is retracted, those pins should not make contact.

If they are making contact when the pedal is at a resting state, the switch should be replaced.

The pedal setup is not like in other vehicles, where depressing the brake pedal depresses the brake switch. Its completely the opposite, when you depress the brake pedal, the brake switch is released.

Those two pins, 5 and 6 make no contact with the ABS module or PCM. If what you're saying is the ABS light only comes on when the brake pedal is resting, then you have another problem, especially if cruise and the brake lights work properly.

If you want to test this, remove the brake switch and manually actuate it in your hand, keeping in mind that depressing the plunger is like letting your foot off the brakes.
 
OP
OP
R

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
This is my brake switch:
Brake depressed and switch extended
pins 1 and 2 continue
pins 3 and 4 does not continue
pins 5 and 6 does not continue
Brake released and switch retracted
pins 1 and 2 does not continue
pins 3 and 4 continue
pins 5 and 6 continue
If i remove the brake switch the abs and park lights stay off
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
Something is wrong then. I'm not sure if the service manual is incorrect, or there is a mistake in what switch is installed in your vehicle.

Pins 5&6 and pins 1&2 should only have continuity when the brake pedal is depressed and plunger extended.

When the pedal is resting only pins 3&4 should have continuity.

I'd try to get a part number and match it up with something online.

Do your brake lights stay on constantly until you actually hit the brakes?
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
If your brake lights stay on until you actually hit the brakes, i'd say you have a faulty brake switch, or the wrong part. You can get replacements at autozone for $10-15.

I'd go get one of those and hook it up and test it by hand just to see if it works. If not, as long as you dont scratch it up, you should be able to return it if thats not it, or they gave you the wrong part.
 
OP
OP
R

RamV10-

Junior Member
Joined
Dec 17, 2016
Posts
13
Reaction score
1
Location
Italy (Reggio Calabria)
Ram Year
1999
Engine
8.0L Magnum V10
Today I received the package from the USA with the new brake lamp switch. I replaced it with the broken one but nothing the abs light is always on just release the pedal
 

dudeman2009

Senior Member
Joined
Feb 9, 2016
Posts
1,562
Reaction score
208
Location
Arizona
Ram Year
2001 1500 Sport with enough electrical modifications to make my brain hurt
Engine
Magnum 360
I'll have to read through everything again, I remember your problem, but not the details.
 
Top