Fed up with Car..
Thread Starter
Burning Brakes
Joined: Oct 2009
Posts: 962
Likes: 61
From: oswego ny
Fed up with Car..
My 2006 uhg.
Long story short.- I took out my aftermarket Head Unit and installed a Alpine head unit. And added the PAC TR-7 unit that wire's in behind radio to fool (deck) that ebrake is on.. THEN after starting car ABS light came on..and code of C0121..... I rechecked everything, and all i could figure is it was a fluke and my ABS unit took a crap. So i then removed the PAC unit and added a three wire video bypass park brake over ride and still the same issue...
So ive been ignoring it and driving car for x amount of weeks with ABS light on and code CO121..in which G.M. say's is ABS unit or fuse or wiring to ABS.
Now this morning i get in the car and start it and dash shows E brake is on when it isn't and serv veh pop's up . And i lost my steering assist..as whole abs system is down..
So at work this afternoon i finally was able to check voltage to ABS (OK) and scanner said unable to communicate with ABS, and ECM is unable to communicate with ABS UNIT.. And now i can only go as far as seeing a code of U0121 (lost communication)...Rechecked fuses, (good).
So any info would be great guy's... Im still thinking ABS unit.
Oh and i did unhook every thing when first problem came up and still same issue..
There is a possibility that i hit acc power to ground as stupid me never unhooked battery -whoops
Long story short.- I took out my aftermarket Head Unit and installed a Alpine head unit. And added the PAC TR-7 unit that wire's in behind radio to fool (deck) that ebrake is on.. THEN after starting car ABS light came on..and code of C0121..... I rechecked everything, and all i could figure is it was a fluke and my ABS unit took a crap. So i then removed the PAC unit and added a three wire video bypass park brake over ride and still the same issue...
So ive been ignoring it and driving car for x amount of weeks with ABS light on and code CO121..in which G.M. say's is ABS unit or fuse or wiring to ABS.
Now this morning i get in the car and start it and dash shows E brake is on when it isn't and serv veh pop's up . And i lost my steering assist..as whole abs system is down..
So at work this afternoon i finally was able to check voltage to ABS (OK) and scanner said unable to communicate with ABS, and ECM is unable to communicate with ABS UNIT.. And now i can only go as far as seeing a code of U0121 (lost communication)...Rechecked fuses, (good).
So any info would be great guy's... Im still thinking ABS unit.
Oh and i did unhook every thing when first problem came up and still same issue..
There is a possibility that i hit acc power to ground as stupid me never unhooked battery -whoops
Last edited by carls2004; Aug 24, 2017 at 05:31 PM.
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
if you did put power to ground and caused a spike things may have died. i killed a deck once this way
Thread Starter
Burning Brakes
Joined: Oct 2009
Posts: 962
Likes: 61
From: oswego ny
So i went from one ABS UNIT code that is usually bad unit then drove for X amount of weeks ,, and then system got worse and No ABS OPERATING ..And now car sits in driveway with no power steering assist as abs sends signal to rack.. Big downer..
But i went ahead and got a used unit coming with 30 day return. So i hope i can narrow the issue down...
Thread Starter
Burning Brakes
Joined: Oct 2009
Posts: 962
Likes: 61
From: oswego ny
Just some more info.. I diag that my head unit install had no way of affecting the abs system as it is not on any communication with the abs.
So with futher diag at abs and ecm it showed abs module was bad...
Swapped in a good used one and my issue is fixed....
So with futher diag at abs and ecm it showed abs module was bad...
Swapped in a good used one and my issue is fixed....
Drifting
Joined: Nov 2016
Posts: 1,820
Likes: 411
From: Somewhere in the middle of Kansas
