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Dvorak
Senior Member
United States
95 Posts |
 Posted - 10/31/2013 : 05:43:34 AM
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| I have a bad ECU on a Wabco full power brake system (12v coming into it but no voltage going to one of the motors on the back side). My question is this: Have bad motors been burning out the ECU's and if so, should I be replacing the entire HCU? I'd hate to install a new computer only to have it burn out right away. Also, I've searched the previous posts but I've been unable to locate a part number to replace the pump motors. Has anyone found anything on these? Thanks in advance. |
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Dvorak
Senior Member
United States
95 Posts |
Posted - 11/19/2013 : 04:08:37 AM
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Here's an update on what I've found for this vehicle: I replaced the ECU and unfortunately, the problem still existed. I ended up ordering and installing a new HCU and that took care of all my problems. Before I returned the other one for a core, I decided to dismantle it to see inside the belly of the beast to try and learn something about it. When I pulled out one of the pumps, it sort of fell apart in my hand. I then hooked up the corresponding motor to voltage and it sounded a lot different than the other one. I'm not a certified failure analyst by any means, but from the evidence I've seem, I believe that the pump started having problems which burnt the motor which ended up taking out the ECU (remember, I did not have enough voltage on the ECU "towers" to energize my headlamp (voltage drawing test light)).
Lesson learned: The next time I run into this situation with a factory installed HCU (this one was from an 06), I'm going to bite the bullet and install the whole works right away. The 5-6 year range seems to be the lifespan of these systems, from my experience. I hope this information might help out the next guy.
Also, I don't know enough German to know how to order the pump motors directly from the manufacturer and that wouldn't have fixed the underlying problem anyway! |
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Bus Tech II
Senior Member
121 Posts |
Posted - 11/19/2013 : 04:45:54 AM
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| We have replaced several of these units and unfortunately we usually end up purchasing the whole thing. They are very expensive but the way I look at it is does safety of children have a price tag?? They can be hard to diagnose. The codes that seem to be right on the money are the pressure gradient codes which means pump failure, But I would have to agree with you in replacing the whole unit. |
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mastertech
Advanced Member
274 Posts |
Posted - 11/19/2013 : 9:21:24 PM
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| You can kind of tell when the motors are starting to go . One might take a bit longer to shut off than the other and they will make a slightly different noise. As far as replacing the whole unit instead of just the hydraulic part Id give the nod to the whole thing. I am seeing more and more intermittant "ghost codes" like low amplitude and air gap to large when detailed testing and parts replacement shows no real defect. I am beggining to think the ecu's are failing electrically causing these codes. |
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earl1412
Senior Member
101 Posts |
Posted - 01/07/2014 : 7:18:44 PM
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quote:
Originally posted by Dvorak
I have a bad ECU on a Wabco full power brake system (12v coming into it but no voltage going to one of the motors on the back side). My question is this: Have bad motors been burning out the ECU's and if so, should I be replacing the entire HCU? I'd hate to install a new computer only to have it burn out right away. Also, I've searched the previous posts but I've been unable to locate a part number to replace the pump motors. Has anyone found anything on these? Thanks in advance.
I have found a site for part numbers needed for motor/pump replacements only here it is
http://www.meritorwabco.com/MeritorWABCO_document/TP1349.pdf
This pdf shows what is needed to get correct parts for replacements due to age or code numbers found on various HPB units.
Good Luck!
earl |
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Wabco questions...
