Wondering if there is a valve in the abs module. Just put al new pads, rotors, and calipers on the rear. No bubles in the fluid, no sign of being abnormal...

Blead the brakes, and abs light came on, fluid is good in the resivouir... ***

 

Turn the ignition key to the OFF position.Disconnect the CAB 14-way connector and leave disconnected for 5 seconds.Reconnect the CAB 14-way connector. Turn the ignition switch to the RUN position did the light turn off?
Disconnect the harness connector from the differential pressure switch Is the brake warning lamp still illuminated? NO then the pressure differential switch has shuttled. Try bleeding the front brakes to center valve. If you can get code from ABS module (will need to have DRB3) or have a friend with a code reader. Check PDF file attached.

BLEEDING ABS BRAKE SYSTEM
ABS system bleeding requires conventional bleeding methods plus use of the DRB scan tool. The
procedure involves performing a base brake bleeding, followed by use of the scan tool to cycle
and bleed the HCU pump and solenoids. A second base brake bleeding procedure is then
required to remove any air remaining in the system.
(1) Perform base brake bleeding. Refer to base brake section for procedure.
(2) Connect scan tool to ABS diagnostic connector.
(3) Select ANTILOCK BRAKES, followed by MISCELLANEOUS, then BLEED BRAKES.
Follow the instructions displayed. When scan tool displays TEST COMPLETE, disconnect
scan tool and proceed.
GENERAL
INFORMATION

 

I have done my brakes several times and have never needed a scan tool.....bleead all four brakes, starting from the left rear then right rear then the two fronts, make sure to NOT pump the pedal. Start truck let idle have help push down and hold....then you crack bleeder for just a second then close...do this all the same on all wheels. several times...all will be good. never had an issue, and no need for a scan tool.

 

thats what i did, think i found the issue though...