Ok, this is a long one. ABS light is almost constant on ( one amigo). Sometimes ABS and Traction Control lights are on at the same time ( two amigo). And for a brief moment Down Hill, Traction Control and ABS were on at the same time( three amigo). ABS TC are defiantly not functioning.

BUT no ABS codes! None! The only code I get is when I switch to the OBDII function of my reader and I get P1590. I try to erase the code, scanner confirms but ABS light is still on. I am using a solid scanner that I have used many times to diagnose and fix ABS trouble. New shuttle valve was installed last year that took acre of previous Three Amigo flare up. Pads and rotors have less than 3k miles. Again, there are ZERO ABS codes and I have used my code reader (AUTEL 619) many times to read ABS faults so I know it’s not a reader problem.

P1590 as explained by Disco Mike in 2008:

“1590 is a rough road/ABS fault that normally will also show up when the ABS is having problem with the lights coming on and off or on all the way.
It can be clear with a proper scanner and is not being caused by any other ABS part.”

dunno if he was right but it adds up with what I am seeing.


I have researched this on all the forums but of course none of the threads include a solution, they all get highjacked or are simply abandoned before a solution is posted.

I know enough about the ABS system to know that if the hardware is acting up, shuttle valve, wheel ABS sensor etc. that it WILL throw a code.

Does anyone have specific knowledge about a P1590 code NOT accompanied by any ABS codes and how to fix it?

thanks,

frank

 

If it's the internal connector inside the WABCO unit itself (main reason I perform Option B besides for insulation rotten on shuttle valve switches) it won't toss a hard fault. It will just trigger the 1,2,3 amigo's and usually upon a key cycle the 1,2,3 amigo's are gone until that internal connector gets bothered by a vibration or bump in the road which causes it to freak out again.

The only time I've seen a P1590 fault stored and no ABS faults was from the internal connection failing or the shuttle valve switch insulation causing soft faults which set the lights off while driving, but when you performed a key cycle the system was good to go again until the next time it had an internal ground fault. Then I had the P1590 with ZERO faults on a vehicle which already had Option B installed on it & it was due to a poor ground on the Option B harness. Crank the D2 and let it idle and the amigos would get triggered, go in with the Nanocom or the iCarsoft LRII and only fault present was P1590. Clear it ABS light was on like it should be drive it and it would clear. Then turn it off, come back out the next day and bingo same routine, but this was on a D2 which already had Option B performed. So if you're getting that without Option B I would think the internal connector inside the WABCO = grounding out.

 

Frank, when you installed the new shuttle valve switches did you also do Option B?

 

just the shuttle valve. Everything I have read indicates that it’s the SLABS that is acting up. Wouldn’t bad wiring in the ABS block throw a hard ABS related code readable by my autel 619 that I’ve used to successfully diagnose and fix past issues?

 

No when the internal connector acts up = soft faults usually which go away after a key cycle until it vibrates around enough to trigger the lights again.

 

Best 4x4: Not to hijack this thread too, but I have a similar, possibly related, issue. I did the option B fix last week, and it solved the three amigos. I cleared the 1590 code and it hasn’t come back. The only problem is that now the traction control comes on when I am taking a right turn and moving a slow speed. It feels like the ABS modulator is braking the driver side front brake when the TC light comes on. I suspect it has something to do with a faulty speed sensor, but I don’t have any codes. I also have the Autel 619 that will read the ABS codes, but I understand there are some code readers that show “live” ABS data that will show outputs from each of the sensors and which may help diagnose my issue and Frank’s issue. Do you have a code reader that will tell you live information on the ABS sensors? I’m in your area this week. I see several threads with this traction control when turning right issue on this forum, but I don’t see any solid resolutions. Also, I’ve changed all of the hubs over the years and they have new speed sensors with them obviously. I’m wondering if just a sensor is bad and can be replaced or if the whole hub needs to be replaced or some other electrical issue.

 

Nanocom can do live data on the wheel sensor speeds and so can the older lynx system if I'm not mistaken. Sure a Hawkeye can as well.

 

Do you know if the the Snap On will do live data? I have access to one and have been chasing a very intermittent fault for a wheil.