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SPN 521 - Robert1966Garcia - 05-01-2020

Good morning to one and all!
I have a 2015 International Prostar with a 2350 pushing a Eaton ultra shift automatic.
It also has the wingman collision mitigation system. I have code SPN 521 fmi 2 active on the dash.
It has the cruise no working and the trans is hard to get into neutral as you slow to a stop. Have read but can not find the existence of a brake pedal position switch, the brake lights work as they should and the trans shifts from park to drive and vis versa.
Have not found any help on line so I am turning to you folks for help. The dealer wants 250.00 for a brake light switch which I can find online for less than 40.
Thank you in advance for an help you might be able to give.

Update, I have been off for a few weeks due to COVID and low freight rates but have tried to figure the problem I am having and have learn the following.
1 the brake light switch is not the problem
2 the low air pressure sensor that the trans, brakes and traction control depends on is not it.
3 the issue, that I could find is not in the harness, connectors, tail lights Or tail light harness.
4 it only happens when the brake pedal is depressed and released, and happens if it is or is not in gear as well with the park brakes released or set.
5 you can set with your foot on the brakes till your leg gets tired and when you loose the slightest amount of air It will set the code.

I have the DLB program but don’t really know how to use it. Is there someone that I could talk too or pay them to remote in and give her a look???
I don’t want to be on the road with a check engine light on and or have a bigger problem away from home and my tools.
Thanks to each and everyone that even reads this post and the update, for your time!!


RE: SPN 521 - kozakvod - 05-01-2020

Cummins Fault Codes for SPN:521 FMI:2
4526 Amber Brake Pedal Position - Data Erratic, Intermittent, or Incorrect

Possible causes of this fault code include:
A malfunctioning brake pedal position switch
A short circuit to ground in the OEM harness
An open circuit in the OEM harness

QuickServe (if you have it, it's free if you don't) https://quickserve.cummins.com will have more specific info on troubleshooting.


RE: SPN 521 - Rawze - 05-01-2020

could be tarnished pins form someone power=-washing the truck at the cab plugs too. -- never allow the truck wash facilities to power-wash under the hood of a truck.

just some thoughts. see this kind of issue a lot around here.


RE: SPN 521 - Robert1966Garcia - 06-12-2020

Update, I have been off for a few weeks due to COVID and low freight rates but have tried to figure the problem I am having and have learn the following.
1 the brake light switch is not the problem
2 the low air pressure sensor that the trans, brakes and traction control depends on is not it.
3 the issue, that I could find is not in the harness, connectors, tail lights Or tail light harness.
4 it only happens when the brake pedal is depressed and released, and happens if it is or is not in gear as well with the park brakes released or set.
5 you can set with your foot on the brakes till your leg gets tired and when you loose the slightest amount of air It will set the code.

I have the DLB program but don’t really know how to use it. Is there someone that I could talk too or pay them to remote in and give her a look???
I don’t want to be on the road with a check engine light on and or have a bigger problem away from home and my tools.
Thanks to each and everyone that even reads this post and the update, for your time!!


RE: SPN 521 - Rawze - 06-12-2020

before going further down that rabbit hole, simply replace all the little fuses in the fuse panel... even if they look perfectly fine. Lot of ghost errors from tarnished fuses on those prostars, it is a very common problems for them. ref: http://rawze.com/forums/showthread.php?tid=1514&pid=12861#pid12861

It is cheap to do and eliminates one more thing on the list of possibilities.


RE: SPN 521 - Robert1966Garcia - 06-23-2020

(06-12-2020 )Rawze Wrote:  before going further down that rabbit hole, simply replace all the little fuses in the fuse panel... even if they look perfectly fine. Lot of ghost errors from tarnished fuses on those prostars, it is a very common problems for them. ref: http://rawze.com/forums/showthread.php?tid=1514&pid=12861#pid12861

It is cheap to do and eliminates one more thing on the list of possibilities.

Have done all that and the problem still persists. DLB is no help, insite nor jpro either, not going to dealer. Have wondered if it could be a parameter or other setting.


RE: SPN 521 - Robert1966Garcia - 06-23-2020

What is the EBC1 on this Prostar an were is it located. Also how does that effect the braking system??


RE: SPN 521 - Waterloo - 06-24-2020

On my 2008 ProStar I had the TC, ABS, Engine brake and Red triangle of death lighting up every once in awhile on my dash. I wound up at the dealer, they told me it was my “compass”... I said, “What compass”

He said, “This compass, right here in the odometer screen.”

Then he asks, “Where is your compass?”

Me, “Hell, I didn’t know I had one!”

Long story short, all of the above items in my list of idiot lights that lit up, are wired through the N, S, E, W compass module. He used DLB to discover that. So in other words, it could be any number of sensors or modules in the truck. I never would have figured any of this out on my own. Sometimes the dealer is it.


RE: SPN 521 - david24 - 06-24-2020

(06-24-2020 )Waterloo Wrote:  On my 2008 ProStar I had the TC, ABS, Engine brake and Red triangle of death lighting up every once in awhile on my dash. I wound up at the dealer, they told me it was my “compass”... I said, “What compass”

He said, “This compass, right here in the odometer screen.”

Then he asks, “Where is your compass?”

Me, “Hell, I didn’t know I had one!”

Long story short, all of the above items in my list of idiot lights that lit up, are wired through the N, S, E, W compass module. He used DLB to discover that. So in other words, it could be any number of sensors or modules in the truck. I never would have figured any of this out on my own. Sometimes the dealer is it.
I may need to check this out as well. My abs, tc, and warning triangle comes on and goes off. I changed the abs sensor that was showing a problem. Worked for a good while but then came back on