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Alex Olsen
Alex Olsen,
Category: Medium and Heavy Trucks
Satisfied Customers: 93
Experience:  Lead technican at Astleford international trucks
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I have a 2007 International 4300 with an Allison auto and

Customer Question

I have a 2007 International 4300 with an Allison auto and hydraulic brakes. Vin:7H435672 Lost brake pressure completely today when I got into the truck. Brake pressure light and buzzer. The master cylinder has been changed recently but the problem existed prior to that. The issue always starts the same sometimes the brake pressure light will flicker on and off, sometimes it will stay on and after truck warms up it turns off. Just very intermittent. Almost like a wiring issue. Seems to come on the most when the truck sits overnight like air is getting into the system, but there is no fluid loss. It has 3 codes currently Axle 1 pressure loss and Axle 2 pressure loss. The third codes is the one that always accompanies the brake pressure light and eventually leads to the other 2 codes and complete brake failure: 128 247 2 SID Engine #1-Brake Pedal Switch #2 Data Erratic, Intermittent, or Incorrect. Not sure where this sensor is located. I know that the Brake pedal switch #1 is located on the master cylinder along with brake fluid level sensor. No sensor on brake pedal.
Submitted: 14 days ago.
Category: Medium and Heavy Trucks
Customer: replied 14 days ago.
Also when it throws the brake pedal #2 code the abs pumps do not work. This is what probably leads to complete brake failure? cycling key to start position doesn't activate pumps like usual. Pressing brake pedal doesn't turn on pumps. Checked fuses, wiring, and even tested harness pins to WABCO ABS module according to their readily available bleeding and troubleshooting procedures available online.
Customer: replied 14 days ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 14 days ago.
I do not need a live phone call.
Expert:  Alex Olsen replied 14 days ago.

hi im alex i will go over this and get back to u have a good thanksgiving

Expert:  Alex Olsen replied 12 days ago.

ok lot of good background info here thanks for that, do you have wabco tool box software? or how are you reading the codes?

Customer: replied 12 days ago.
I'm just using a HD generic code reader. As of now I have gone through and checked all cables and harness connectors. I also unplugged cleaned and greased every single connector that is coming from the pump. Pump still won't turn on KOEO or by pressing the brake pedal. Like it is not getting the sensor input it's supposed to be activated.
Expert:  Alex Olsen replied 12 days ago.

yes this is a full power brake system the ECUs go bad all the time i wouldnt doubt that is the issure here, if you had wabco tool box you can see all the switch and sensor inputs and what the accumulator pressures are at, might need a complete unit

Customer: replied 12 days ago.
Complete ecu or complete abs unit. I have another truck identical to this. What's all involved in taking off the ecu? I will try swap the ecus and report back. I talked to international. Have you seen ECU failures where it's intermittent and sometimes works and sometimes doesnt? Or generally when the ecu fails is it completely dead?
Expert:  Alex Olsen replied 12 days ago.

could need a complete ABS unit, but usually ECU is the problem, yes ECU failures are almost always intermittent, easy to swap its just 4 bolts holding it on

Customer: replied 12 days ago.
Pulled the ECU there was some rust/corrosion in one of the nipples. Cleaned it up and made sure all the connections were clean on the ECU. Reinstalled it and still no ABS pumps. At this point I went to the other truck and pulled a good known working ECU. Put that in and it still doesn't work. Could this problem be caused by the master cylinder? Would no pressure in the lines from the master cause the pump not to cycle when pressing the brake or turning key to the on position. Pump always cycles when key is first put in on position. Just thinking its the master because it was a reman, and I've had multiple problems with reman parts before.
Expert:  Alex Olsen replied 12 days ago.

here is wiring diagram, master shouldnt have any thing to do with system running when you turn the key on

Expert:  Alex Olsen replied 12 days ago.

no that it makes much difference but put the ecu off this truck on the other one and see what happens

Expert:  Alex Olsen replied 12 days ago.

see if you have the same codes

Customer: replied 12 days ago.
I will do that. I'm going to double check that the correct pins are getting the correct power tomorrow, again. After that I'll probably pull the entire pump and swap it with the other one. Looking at that electrical diagram there is no way for both the pumps not to work unless it wasn't receiving ignition 12v+ or Brake switch 12v+...but does are separate circuits, and I don't remember if the pumps run with the ignition off when you press the brake pedal. Does ignition have to be on for the pumps to work or do they work on brake or ignition?
Expert:  Alex Olsen replied 12 days ago.

no you do not have to have the key on, ignition off hit the pedal and they should come on as well

Expert:  Alex Olsen replied 12 days ago.

sounds good talk, to you later have a good night

Customer: replied 12 days ago.
Well checked the pins again. Pump 1 and 2 both have good positive and ground. Solenoid good positive and ground. Ig notion has good positive. Brake switch feeds back from brake fail. I think that's because they are on the same 5A fuse, but works when pressed. Other than that I can't see anything from stopping the pump. Any other ideas other then to pull the unit?
Expert:  Alex Olsen replied 10 days ago.

no if the pumps have good power and ground but are not running i see no other option but to pull the unit

Customer: replied 10 days ago.
Swapped the pumps today. Ran for about 2 minutes normally. Worked when brake pedal was pressed and key on engine off. No brake pressure lights or warnings. Not active code brake pedal switch 2 keeps coming back when truck Is restarted. Still had no brakes. Tried bleeding master all the way back to the calipers following procedure and pressurizing tank to 35 psi.
Customer: replied 10 days ago.
Still nothing. Swapped master. Same outcome. I saw in the fuse box that there is a hydraulic spool valve fuse, and two other hyd fuses, however I cant find what pin that corresponds with in the diagram. Is that the solenoid pin? What criteria has to be meet for the pump to run. Would one or more faulty abs sensors confuse the pump. The only time I can get the pump to run is to pull the main power and plug it back in at the pump and it runs and immediately shuts off.
Expert:  Alex Olsen replied 10 days ago.

The spool valve fuse I think runs to

Pin 17 I believe , those 3 fuses should be the ones in the diagram that say mini fuse 4001

Customer: replied 9 days ago.
Looks like it was the pump. Pump works when brake pedal is pressed, but only the rear brakes work. I'm guessing there is air in the system.
Expert:  Alex Olsen replied 9 days ago.

ok i was going to tell you these hold a ton of air but wasent sure how much you had bled them yet, with wabco software there is a bleed procedure you run to bleed them out and that take a while i have never done one with out that so im sure it will take a while

Expert:  Alex Olsen replied 9 days ago.

please remember to rate my service when you get a chance, i receive no compensation until you rate me, i will continue to assist with any followup questions after rating so rate with confidence, thanks

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