2015 international 4300 Range inhibited, brake pressure, alarms

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by BreakOnThrough, May 31, 2020.

  1. BreakOnThrough

    BreakOnThrough Bobtail Member

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    May 31, 2020
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    Hey, seen many of fixes on this board over the years. HeavyD , I’m going to be bald by Monday if I keep second guessing myself.
    Truck will not move 95% of the time. I have NEDS/Wabco ABS software. Atleast 6 short to ground codes in Wabco EBCM. Including devices the truck is not equipped , like hydraulic parking brakes and ATC codes. Truck has neither system. No CAN/communication codes. HPB hydraulic brake pressure is actually in spec at 1950-2100 psi front and rear. So here is the skinny
    Jump in and fire the truck up. Abs pumps run , pressures are fine. 95% of the time the yellow triangle, red stop sign ,ABS, brake pressure and audible alarm are lit or sounding off. As soon as you push the button for drive ( Allison 2000 series ) the range inhibited light lights up and no engagement.
    I split the Wabco EBCM off of the HCU and found a lot of rust on pins/connections. Thoroughly cleaned and no difference. I have a code for the brake travel switch on master cylinder and the part is ordered. I understand the trans wants to see a clean brake Travel switch signal, but when the truck does engage trans the brake pressure /audible alarm are off.
    Not related but maybe is that I know the truck was rolled on it’s side 2 years ago the crew been driving the truck with ABS light for 2 years because RF reluctor wheel is damaged and my old boss didn’t want to repair.
    What doesn’t add up is The brake pressure light and alarm are making me worry. The abs EBCM is 1600 dollars. Has anyone seen a Wabco module fail with multiple “ short to ground codes “ or FMI 6 noted with codes? I finally talked owner into buying Neds/Wabco software and my first go round with it had to be a dandy. Should have shipped it but I’ve mostly always fix em.
     
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  3. Heavyd

    Heavyd Road Train Member

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    The range inhibited warning is usually because the trans is seeing a gear selection while either the park brake is still applied, and/or the service brake is not applied when shifting out of neutral. The pressure warnings are normal when first starting up as the system pressures need build up enough to release the parking brake, if it has the hydraulic release type, and refill the accumulators. So what happens if you wait for the system to build up pressures and the pumps stop?
     
  4. BreakOnThrough

    BreakOnThrough Bobtail Member

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    May 31, 2020
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    Thanks for responding! It runs pumps straight away as designed with good pressure on both channels, front and rear straight away. 1800-2100 psi. I pump the pedal watch pressure drop a bit and Then pumps run to fill accumulators right up to 2100 psi.
    When truck does engage trans I don’t get the “ brake pressure “ light or the audible alarm.
    When the brake pressure light and audible alarm go nuts, the truck will not go in gear and range inhibited lights up.
    What grabbed my attention with your response is the fact that I have parking brake codes.
    upload_2020-5-31_21-4-38.jpeg
    The truck has a manual parking brake and light on dash goes on when I pull Ebrake and off when released. I wonder if these weird short codes are confusing the trans module etc. It has parking brake codes for a system the truck isn’t equipped with. What ya think?
     
  5. BreakOnThrough

    BreakOnThrough Bobtail Member

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    May 31, 2020
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    Also just for the full picture, that code capture is right after I put Wabco EBCM back on hcu. Earlier code capture didn’t have the ground connection code. Here’s NEDS capture
    upload_2020-5-31_21-10-4.jpeg
    Here’s original capture before I touched anything
    upload_2020-5-31_21-10-52.jpeg
    Wonder if the module has failed for abs ?
     
  6. BreakOnThrough

    BreakOnThrough Bobtail Member

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    May 31, 2020
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    So, it was my first rodeo with the HPB Wabco brake system. Oddly enough, I’m pretty certain the abs module lost its parameters somehow. Jumpstart? Low batteries? No idea but each is possible with crews that run these trucks. When I wrote the parameters I pulled from original module and set into new module, I still had weird codes etc. Except now the parking brake travel switch was N/A as I would expect. So I grabbed the parameters from its twin, same year, same brakes/options. All was well. Drove it for miles. 2 hours total. Next day, today, I move it around a couple times and it’s fine. This afternoon, I finally get a chance to test drive again before I ship it and I notice pumps running way too long. Bring it to shop, hook up Wabco Toolbox and now it has low front pump pressure. Pump will not run when commanded. Not sure if a fuse blew. End of day. I’m going to leave this opinion here. Replace the entire HCU if you have similar issues as posted in this thread. I tried to avoid the 7k hit and at this point I’m probably buying a 1600 known good Wabco ecu test unit Just replace the unit and be done with it. That’s what the dealer typically will do because I’m willing to bet they been burned trying to repair components on this system.
     
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