Bus made morning route with no issues. Bus parks near loading area for the day. PM route drivers calls with no start issue. Engine seems to spins more rapidly than normal. Brake fluid level light and pressure lights on also. Driver takes sub bus on route.
Bus sits overnight. I inspect and find brake reservoir empty. Further inspection shows leak at ANTI LOCK BRAKE MODULE on frame rail. I think its a reservoir issue on top of the unit but not sure at this point.
Will a 597 2 BRAKE SWITCH CIRCUIT FAULT cause a no start?? is this related to the low fluid level light also?
Had bus shown signs of issue prior to end of route I might look for other issues. The brake fluid issue has me thinking its the cause of the no start. Possible through ECM maybe??
If so is there any way to make it run again so as to limp it to the shop for repair of the leak??
Its 3 sport and UIL month so I am hurting for enough busses to cover everything. Ugh!!
I think you have 2 separate issues. Are you saying the SAHR can is leaking? like through the center of the housing? Check your ICP while cranking and look for the tach to move to show cranking speed.
I think you have 2 separate issues. Are you saying the SAHR can is leaking? like through the center of the housing? Check your ICP while cranking and look for the tach to move to show cranking speed.
Edit made to post above. Its the anti-lock brake assy that is leaking from the top reservoir I think. Needs a good washing before I can dig into it.
I'll check for voltage at the IPR and see if I have the plumbing to check ICP pressure at cranking in the am. UGH!!
I hear Wabco has some updates for the anti-lock unit so my guess is they include my leak issue. Double UGH!!!
I think you have 2 separate issues. Are you saying the SAHR can is leaking? like through the center of the housing? Check your ICP while cranking and look for the tach to move to show cranking speed.
The more I thought about it the dumber my assumption sounded. We all know what they say when assuming something....
Anyway, the bus started the next morning like there was no problem. Best I can tell this bus is also exhibiting the signs of low oil pressure to the injectors when the oil is warm. Ugh. I still haven't repaired its sister bus either. Guess I need to spin some wrenches on these things.
Now for the brake issue. Has anyone replaced the reservoir on a Wabco Hydraulic Power Brake (HPB)? Mine has split at the seam weld and is leaking all the fluid out of the master cylinder. I know that cleanliness is my best friend here but are there any other words of advise on the reservoir swap?
The cap on that large flat reservoir has to vent. If it does not vent quickly it will stress the reservoir, increase pump time for brake release and shorten pump life. We change the caps frequently.
If this is the original pump unit I think just replacing the whole unit is the way to go. Those motors start failing after 5 years and you will just be back in there tearing it apart again. The caps on the fluid tanks have a water resistant membrane/filter. If they get wet or dirty they will set a code for low pressure gradient as they slow build up pressure. A tip is never let anything get on the cap, water ,brake fluid dirt as it will plug the microscopic holes right away. So keep the pressure washer away when cleaning.
If this is the original pump unit I think just replacing the whole unit is the way to go. Those motors start failing after 5 years and you will just be back in there tearing it apart again. The caps on the fluid tanks have a water resistant membrane/filter. If they get wet or dirty they will set a code for low pressure gradient as they slow build up pressure. A tip is never let anything get on the cap, water ,brake fluid dirt as it will plug the microscopic holes right away. So keep the pressure washer away when cleaning.
I'm going to throw some parts at this unit and see how it goes. That remaned unit is SPENDY!!!
Thanks for the tip on the cap and the pressure washer causing issues.
Brake issue causing no start??
Posted - 03/24/2015 : 12:13:33 PM
