N14 - got ecm codes 123, 132 & 352

Discussion in 'Trucks [ Eighteen Wheelers ]' started by joecitizen, Dec 24, 2011.

  1. joecitizen

    joecitizen Light Load Member

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    I have a '93 FLD120 with an N14. Lately the red stop engine light has been turning on sporadically (displays for a few seconds the goes out) so I went and had any fault codes pulled from the ecm. The codes 123, 132 & 352 were shown as inactive.

    I searched and found the description of each code:

    123 Intake Manifold Pressure Sensor Circuit

    132 Accelerator Position Sensor Choice

    352 Sensor Supply Circuit (although on the ecm printout it has a description of cruise control/PTO, engine brake don't work. My cruise control indeed does not work, I do not have a PTO and my jakes work fine.)

    Questions:

    Would the 123 code be the same as the boost sensor? Reason I ask is cause that sensor has recently been replaced.

    Would the 132 code mean something is possibly up with the throttle position sensor on the accelerator pedal?

    I am baffled by the 352 code. Is it possible the other two codes could be the cause of the 352 code?

    I have a print out of the codes and noticed a fault parameter of Total ECM Time (Key On Time). For example, on code 123 is 36:43:44 (hh:mm:ss), what does it mean and how do I interpret it? For the same code I also see column PID that has a value of 102 and a column J1587 FMI with a value of 4, what does these mean?

    Things already replaced:

    Engine position sensor, fuel solenoid, boost sensor, speed sensor (on back of trans), power and ground wires from batteries to ecm, battery cables and ignition switch

    I could go on with questions about the meaning of the other fault parameters, but this is already getting to be a big read.
     
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  3. Prairie Boy

    Prairie Boy Road Train Member

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    I think you have a poor ground and as it searches a path it activates the sensors.
     
  4. vegetto05

    vegetto05 Light Load Member

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    123 is low voltage at the signal pin for the intake manifold pressure sensor (or boost sensor). There are three wires going to the sensor, 5 volt reference, signal, and ground. keep this in mind

    352 code is for the sensor supply. all of the sensors that get a 5 volt reference all feed off of the same circuit. if the wire is shorted to ground, or if a sensor that it supplys to is shorted to ground, then this fault will become active. there are four different sensors in this circuit. intake manifold pressure sensor is one of them. my suggestion is to unplug the intake pressure sensor (located at the rear of the intake manifold) and see if the 352 goes inactive. if it does, then replace the sensor. this will take care of both codes. if it does not then we need to unplug the other three sensors, one at a time, and see when the 352 goes inactive and replace that respective sensor. if the 352 never goes inactive then we have a short to ground in the wiring harness. but just remember that this code is causing the 123 code most likely. i say most likely because there's always a chance to have two problems in the same area, but not likely.

    this code states there is a loss of signal from the throttle pedal. i assume, since you haven't mentioned it, you still have throttle response. if that is the case, then all you have to do is calibrate your throttle. to do this, first turn off the key, then turn on the key, depress 100% and release the throttle pedal three times at a moderate pace. turn the key off for 30 seconds. turn the key back on and see if the code is inactive. if not, we need to unplug the throttle sensor, measure the voltage from the 5 volt reference pin to the ground pin. voltage should be between 4.75 and 5.25 volts. if not, then measure the voltage between the 5 volt reference pin and a good known ground at the battery. if have good voltage, then the ground circuit between the pedal and ecm is open. if we still don't have voltage, then there is an open in the 5 volt reference ciruict between the pedal and ecm. if we do have good voltage and ground, then short the 5 volt reference pin to the signal pin at the harness connector and see if fault 131 comes active. if it does then replace the throttle. if not, then we have an open circuit in the signal wire between the pedal and ecm.

    Total ecm time means just what it says. this is the total time the ecm is powered on by hours:minutes:seconds. the only reason this becomes relevant is if we have many many fault codes and we need to figure which one is the most recent.

    PID, PPID, MID, FMI, and SID are all SAE terms for fault codes. SAE has a standardize set of fault codes. for cummins purposes, these are not needed as cummins has their own set of fault codes you should follow rather than these.

    MID - Messenger Identifier. This tells you which computer is setting the fault code. Engine ecu MID is 128.

    PID - Parameter Identifier. This tells us the sensor, sending unit, or actuator sending the fault. PID 102 is for the intake sensor.

    FMI - Fault Mode Identifier. This tells us the type of failure. FMI 4 is voltage low.

    Useless information, only Volvo (that I know of), uses SAE fault standards. Most everyone else has their own set of fault codes.
     
    joecitizen Thanks this.
  5. joecitizen

    joecitizen Light Load Member

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    Tucson, AZ
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    a couple of months ago i was lost power to the ecm and needed a tow to the shop. new wiring (ground & power) from the batteries to the ecm was installed. i dont know if the code(s) in the computer were cleared when this happend. could these three codes be from that?

    all three of these codes show as being inactive.
     
  6. vegetto05

    vegetto05 Light Load Member

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    it seems to me that they did clear the codes. if they hadn't, you would have still had an inactive 434 code in there for loss of battery power. if it was me, i'd just continue driving it since the codes are inactive. the worst thing, for your wallet at least, is to bring the truck to the shop. when you have intermittent codes like the ones you have, its very hard to diagnose. you may spend a lot of money at this point having someone try to figure it out. but if you continue to drive it and wait until it gets worse, the code may be active all of the time and it will be much easier to troubleshoot.

    i know it sounds ### backwards to wait until a problem gets worse, but in this case, it would be the right thing to do.

    oh and something i forgot to mention, the 132 code is the only code that will turn on the stop engine light and not the check engine light. something to think about.
     
  7. joecitizen

    joecitizen Light Load Member

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    i sorta did this without realizing it. one day engine just turned off while going down the road, like i had turned off the ignition key. this is how the power to the ecm problem i had got resolved. unfortuneately i had just got loaded when this happened. i ended up having to be towed back to the shipper to unload, then to the shop. i really dont want to go through that again, but i also understand what you are saying.

    i went ahead and replaced the throttle position sensor anyways... so far so good...

    ... now on to why my cruise control isnt working and why the ecm thinks the service brake switch is depressed...

    thank you for your help!
     
    Last edited: Dec 27, 2011
  8. joecitizen

    joecitizen Light Load Member

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    Mar 15, 2009
    Tucson, AZ
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    been a few days now since replacing the throttle positions sensor and the only complaint i have is the throttle seems to "kick in" when the pedal is about half way through its range of motion.

    besides the instruction given earlier in this thread about re-calibrating the tps, is there anything else that needs to be done? i have calibrated the throttle as instructed twice and no change.

    originally the throttle pedal had a tps and an idle validation switch. the new tps is an integrated one, so there is no longer a separate idle validation switch. with this newer style tps, do i need to take the truck to cummins and have the ecm tweaked so i can get the full range of the throttle back?
     
  9. vegetto05

    vegetto05 Light Load Member

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    besides calibrating the throttle, there isn't much else you can do. all i can say is to make sure you had the right part installed. although, if you idle the engine, can you go through the full rpm range? what i mean is........ can you say hold the engine speed at 800, 1100, 1300, 1500? if you can't do this, the tps is failed and the engine is only going off of the idle validation switch.
     
  10. joecitizen

    joecitizen Light Load Member

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    Tucson, AZ
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    yes...

    yes...

    truck idles fine, goes through the rpm range fine, well until i bottom out the throttle pedal. everything seems normal, yet i run out of throttle pedal travel. it is like the tps sensor isnt doing anything until the throttle pedal is half way depressed.

    if i provide the part # of the tps i was given, do you have the ability to look it up to make sure freightliner gave me the correct one?

    i hope i am describing what is happening correctly, truck responds great , idles fine only problem i seem to have is i dont get the full range of the throttle pedal.
     
  11. vegetto05

    vegetto05 Light Load Member

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    part number and the last eight of your vin.
     
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