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RHeller1

ABS Fault code

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Any wheels been off recently? Had king pin bushings replaced in mine and wheel sensor didn't make contact. They push in all the way. Pushed in hard and popped right in place. Light went out before even get out of park.

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Brake demand sensors are two transducers in the front and rear circuits of the the treadle valve.  Load sensor is the transducer in the rear suspension.  FMI =2 is commonly dead or intermittent. When they are changed they usually need a re-calibration using ACOM (Bendix Software).  ABS works with this code on but roll stability/ESP doesn't.

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I have this 136 69 2 thing going on with the TCS light on.  Claims load sensor erratic.  When I am going down the road, the pressure displayed for the rear bags moves around in a 3 psi window.  Does that constitute erratic?  I don't think the bag pressure is really moving that much.  Changed out the sensor on the firewall feedthru....no change.   So, do the little sensors put out a DC voltage proportional to pressure or a frequency? I haven't put  a scope on it yet. ( Seems like the frequency would be more work for the controller to read).  

Thanks

Rich

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Not singled.  The tone ring.....it doesn't seem to be related to sensing load on the rear.  But I'll have a look tomorrow.  Are there additional connections in a harness at the back of the cable?

 

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Update - I mentioned the rear air bag pressure on the display varies in a 3 or 4 psi window, going down the road. While sitting still, no variation.  Did another visual inspection of the leveling valve link.....there is some play where it attaches to the axle.   My plan is to eliminate the play, and give it another try on the road......before I get a new link.

I guess the brake computer was right......the signal was erratic, but may have been caused by a mechanical issue.

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Update II -  Did a electrical tape fix to take the play out of the leveling valve end links, just until I get new ends.  Now, going down the road, no variation on the bag psi. 

Observation -  Going uphill, the bag pressure drops 2 or 3 psi, going downhill with engine brake active, bag pressure goes up 2 or 3 psi.    Now, is this because the engine torque tends to raise the frame?

So, my TCS light is still on and the diagnostic page for the brake ECU says the 136 69 2 fault is active.

 

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There's two transducers on the treadle valve for brake demand and one on the rear air bags for load sense (on non-Volvo anyways).  They are just a regular 3 wire air pressure transducer and should scope out just like all the rest.  They have a calibration that ACOM does when they are first installed and sometimes they just need that, but it has the same fault code.  Acom will find the trouble right away.  ACOM is free, but the datalink adapter is not.  We all had to get new USBLink 2 adapters in the last year so it's got to be a good time to find cheap old used Nexiq's out there somewhere, but I guess I've never looked.

And yea, that is torque reaction from a trailing arm air suspension.

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On ‎8‎/‎14‎/‎2017 at 6:30 AM, Mastercraft said:

Update - I mentioned the rear air bag pressure on the display varies in a 3 or 4 psi window, going down the road. While sitting still, no variation.  Did another visual inspection of the leveling valve link.....there is some play where it attaches to the axle.   My plan is to eliminate the play, and give it another try on the road......before I get a new link.

I guess the brake computer was right......the signal was erratic, but may have been caused by a mechanical issue.

I have a 2008 Volvo 780 and the computer is throwing the same code (MID 136   SID 69   FMI 2 ). 

I looked at my leveling valve link and the bottom end has about 1/8 to 1/4 inch play.  The top end has about 1/8 inch play.  I don't know if this is the problem . . . but it seems like the end joints should not be that loose.

My next question is, what is involved in replacing the link.  It would seem like there must be some adjustment to maintain the proper ride height for u-joint alignment. 

Thanks and I love this forum.  I found this link by doing a goggle search on "MID 136   SID 69   FMI 2 "

On edit, am I correct in guessing that I make the new link the same as the old link?

Edited by Refuzn-To-Grow-Up

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This is how to set the ride height on a Volvo 770, which I would expect to be the same as a 780:

 

The rear height adjustment is set by 5 holes in the beam under the air bags (there should be 2 on top, 1 in the middle, and 2 on the bottom).  These holes are there for large adjustments. To fine tune the height, rotate the valve (remove the nut on the valve, rotate the attachment between the rod and valve, reinstall the nut).  Don't bend the rod.

 

The Volvo recommended method of measurement is:

1)      Take a measure of the height of the tire (X)

2)      Measure the distance from the ground to the bottom of frame (Y)

3)      Subtract half of tire height (X/2) from the distance of the ground to the bottom of the frame (Y):
                                Y - X/2 = Z

4)      The result (Z) is the desired distance from the center of the drive axle (usually a welding line) to the bottom of the frame.  7.75" is a typical result.

 

Proper height for the front drive axle on a tandem truck is usually 7.75 to 8 inches (from the weld seam in the middle of the drive axle to the bottom of the frame rail).

 

Proper height for the rear drive axle on a tandem truck is usually 7.25 inches (from the bottom of the leveling valve bracket to the bottom of the bag itself where it curves into the bell).

 

When you set the front drive axle height you set only the left/driver's side and then adjust the right side until the truck is level left to right.  Adjust the height, drive in circles a couple of times and repeat until level.  This only applies if you have dual leveling valves.

 

If you only have one valve, then adjust it on the left/driver's side and the right side should level out by itself.

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As discussed in another recent thread, the leveling link has been upgraded to a new, superior design that will completely eliminate the play and weak link of the leveling system for the rear suspension.

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My issue is now odd.  If I am making a turn from a dead stop or under 20mph, the truck will have no throttle response until the steer wheels are close to straight again.  I am thinking it has something to do with ESC, maybe thinking the rear end is sliding, when in actuality it is not.  Once the steers are close to straight again, full power and all is well.  No other codes besides MID136 SID69 FMI2.  any help here is greatly appreciated.  

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15 hours ago, RHeller1 said:

My issue is now odd.  If I am making a turn from a dead stop or under 20mph, the truck will have no throttle response until the steer wheels are close to straight again.  I am thinking it has something to do with ESC, maybe thinking the rear end is sliding, when in actuality it is not.  Once the steers are close to straight again, full power and all is well.  No other codes besides MID136 SID69 FMI2.  any help here is greatly appreciated.  

Makes me wish my truck wasn't in winter storage. This sounds like what it does but I haven't driven it since September.  When I singled it I put all four sensors in the one axle, two of the wires had to be fixed. The abs and traction lights go out when I first start the truck then come back on soon after. I have yet to determine the exact circumstance. Some times I have no throttle response and it may be during turns, backing up is really bad it feels like the  clutch is not engaging and no throttle. The more I think about it the more I think it is in turns. 

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16 hours ago, RHeller1 said:

My issue is now odd.  If I am making a turn from a dead stop or under 20mph, the truck will have no throttle response until the steer wheels are close to straight again.  I am thinking it has something to do with ESC, maybe thinking the rear end is sliding, when in actuality it is not.  Once the steers are close to straight again, full power and all is well.  No other codes besides MID136 SID69 FMI2.  any help here is greatly appreciated.  

What have you checked in the last year? You've been given lots of good tips above, time to get greasy.

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Just a thought... ABS sensors are also used as the “sensor” for the “Traction Control” to detect slipping or sliding of a wheel position. How do you guys drive your trucks this way with questionable throttle response? 

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Mine just started happening this week.  No new codes or dash lights.  My mid136 sid69 has been an active brake code since I bought the truck last year.  Had no driveable issues till now.  I have checked all wheel sensors or fitment, replaced the rear wire harness.  I would assume a dash light would tell me if an abs sensor was dead...is there a way to ohm them?

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Mines a 2012 VNM with the D 11 and I Shift. It was fine untill I singled it. It sat for a year after I drove IT home from Texas. It started to show a code for Nox sensors and abs traction control. I think the nox is from water in the stack. I thought the abs was from not havingn the second axle hooked up. I mounted the second set of sensors in the drive axle as well two of the wires were damaged and I repaired them. I got the truck ready to go 2 days before we left for vacation. I put 600 miles on it and learned a few things to mediate the problem. It goes better with the trailer airr charged. I will be working on it again this summer.

It is not fun to drive this way.

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