I have a 2004 volvo a30d that I'm having issues with. Seems like the park brake won't release and the guage on the dash for the rear brake pressure will not move. I've pulled all the air valves I can find apart and cleaned them out. Replaced 1 valve on the tank under the bed and the air dryer still nothing. Stop light/triangle is on and won't go away.
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2004 volvo a30d rear brake issue.
- Thread starter alcoo44
- Start date
sfrs4
Senior Member
Pop the cover on the right hand side of the cab under the rear side window, should be a load of air valves, the one your looking for is the one with two solenoids on it and a pressure sensor in the middle (see attached ) check that sensor is working if it is then check the solenoid, if it's not, it's frighteningly expensive!
Attachments
Do you know the specs the sensor and solenoid should be with in?
sfrs4
Senior Member
Not till I'm back at work, and that's not till Thursday unfortunately sorry
Okay let me know and I'll look into it. I did pull that valve apart and clean it out had some slimy stuff inside but that didn't fix it...
Went ahead and replaced that valve and sensor and still doing the same thing.
Last edited:
sfrs4
Senior Member
I am so sorry, i hadn't noticed you had replied. there isn't really any spec's per say, the following is from Prosis
Manual engagement of the parking brake takes place when the two-position switch SW5501 is activated, which means that a request for engagement of parking brake is sent to the control units V-ECU and T-ECU.
Automatic engagement of the parking brake can take place in case of the following events:
○ The parking brake is always active when the machine is started, regardless of the position of the switch.
○ When the software function Delayed stopis requested.
○ Request for activation of electric parking brake from the function Load and Dump brake.
○ If the brake pressure in the accumulators is Not ok (if pressure has been lower than 2.5 bar for more than 1 second). This also generates an alarm.
For continued engagement of the parking brake machine speed must be below 2 km/h.
In the next step the voltage to solenoid valves MA5501 and MA5502 is cut off from the control units V-ECU and T-ECU, respectively. This means that the air to the parking brake's pneumatic system is drained, and the brake pads are applied against the brake disc by spring force. When the pressure sensor SE5501 indicates low pressure, the parking brake light LC5501 is activated. Then the longitudinal differential lock is activated,
Manual engagement of the parking brake takes place when the two-position switch SW5501 is activated, which means that a request for engagement of parking brake is sent to the control units V-ECU and T-ECU.
Automatic engagement of the parking brake can take place in case of the following events:
○ The parking brake is always active when the machine is started, regardless of the position of the switch.
○ When the software function Delayed stopis requested.
○ Request for activation of electric parking brake from the function Load and Dump brake.
○ If the brake pressure in the accumulators is Not ok (if pressure has been lower than 2.5 bar for more than 1 second). This also generates an alarm.
For continued engagement of the parking brake machine speed must be below 2 km/h.
In the next step the voltage to solenoid valves MA5501 and MA5502 is cut off from the control units V-ECU and T-ECU, respectively. This means that the air to the parking brake's pneumatic system is drained, and the brake pads are applied against the brake disc by spring force. When the pressure sensor SE5501 indicates low pressure, the parking brake light LC5501 is activated. Then the longitudinal differential lock is activated,
Do you happen to have a diagram of said valves and accumulators?
Also I tried hooking my diagnostic compute to it but the diagnostic port doesn't seem to have any power.
sfrs4
Senior Member
hi Alcoo44
sfrs4
Senior Member
ok so your vcads/ and service socket don't have power? does your float hold on the tip lever? does the seat belt switch have power? all these are supplied by fuse 3 a 5a I have a sneaky suspicion that the wire to the seat belt switch has been compromised and blown fuse 3.
Fuse 3 is good. That's the first thing I did was check fuses. I haven't checked the relays. And the float did work a year and a half ago when the truck moved. The service socket had 4.5 volts when I checked it before I tried hooking the computer to it.
SlatcoAu
Well-Known Member
I know this is probably something you either tried or may not be possible but have you tried connecting shop air to the line to the park brake and the line the pressure switch is on to see if the brake releases and the alarm clears?
Have not hooked it into the park brake line. I've bypassed the compressor and I've tried hooking into both tanks but neither changed anything.
If I bypass all the valves and send air through the air lines individually I can get the drive brakes to release and set that way. What is wierd is when it's running I get air through the tank behind the cab and air Into the tank under the bed but If I go to the valve on the axle side of that tank there's no air