Pontiac Repair: No rear brakes 1999 pontiac grand am, coolant leak, rear brakes

Question
QUESTION: I have  a 1999 pontiac grand am with no rear brakes and no fluid coming out when I try to bleed them. The front brakes work fine and I have both the brake light on and the ABS. I have read it has some thing to do with the ABS modulator valve assembly.

ANSWER: Hi Jim:

well it depends on what ABS code you have set. But an ABS lamp on should not effect the base brake system unless there is some sort of a suck valveing in the brake vlae assembly which is very odd/rare. these cars have diagonal brakes meaning each chamber in the master cylinder and there are 2 controls one front and one rear brake so it would not be a master cylinder issue. BUT if you try to bleed the brakes on an old car and you press the pedal all the way to the floor you are stroking the master cylinder more that it's usual travel and the problem is then you can damage the master cylinder the area the cyclinder doesn't normally travel can have a buid up of corrosion due to the fact that the fluid absorbs mositure and that mositure corrodes the metal parts and running the cylinder seal over the corrosion damages it's seals. Also the mositure in the fluid can damage the brake valve assembly the same way if the ABS brakes had not been used all summer long and you hit the winter and the first ABS stop you could have a valve hang up in the master cylinder. Like I said odd but it does happen. do you know what ABS code(S) set on this? good luck :)


---------- FOLLOW-UP ----------

QUESTION: First of all I want to thank you for your help. the codes are C1214,1226,1238,1233,1232,and P0302. I do have a coolant leak which I know is a head gasket but I also heard a funny noise coming from the front of the car when I start it. It may be coming from the ABS system from under the battery. I read that there is solenoids and a motor assembly as part of the ABS system.It is hard to get to that unit where it is but both back brakes do not work. I did brake free the two lines at the master cylinder and they both push out fluid so I know it is not the master cylinder. If it is that assembly can you some how disable the system? Car info 1999 Pontiac grand am V6 engine with disc brakes all around. Thank you Jim

Answer
those are all wheel speed sensor codes. and the P code is for a misfire on cylinder #2 which may be the head gasket that is leaking. I would get that fixed first and formost before it does engine damage. that aside. if you like in the rust belt like I do that year car was noted for the EBC to fill up with corrosion and cause all kids of wired issues. the EBCM (control module) is in the left fron wheel well forard of the wheel. pull the wheel well out and take a look at the connector for the ebcm if it's full of corrosion you found part of the problem. it's possably the EBCM is commanded on the rear isolation valves and that is the issue??? start looking there. as for the brake valve it's self it's on the frame under the car. NOT easy to get to!