Why register? ...To Enhance Your Experience
+ Reply to Thread
Results 1 to 19 of 19
Like Tree1Likes
  • 1 Post By LaFireEducator

Thread: Pierce Throttle up in pump gear failure

  1. #1
    Forum Member
    Join Date
    Jan 2002
    Location
    Jamestown NY
    Posts
    28

    Default Pierce Throttle up in pump gear failure

    Here goes another one. Found a similar thread but not a lot of details. Here is our problem.

    1999 Pierce pumper. It has a Detroit Diesel series 40 engine. A Navistar engine. Allison transmission Hale Qflo pump with a Class 1 governor.

    Problem is that when the truck is put in pump gear it will not allow the governor to throttle up. It continues to allow the foot throttle in the cab to have control of the RPM.

    The class 1 governor does have voltage output to increase the throttle but at this point the engine ignors it.

    Had the regional pierce mechanic in for 4 hours plus travel pay and he found nothing. Told us to take it to the Navistar dealer for a new computer. Next at Navistar dealer we try a new engine computer and it made virtually no difference. They said they'd try to debug the throttle problem and after 3 weeks nothing. They said we needed a new body computer, the PMC (pierce micro controller) and it made virtually no difference.

    Now several grand into this and we are basically no closer than when I first looked at it and found the governor putting out power.

    One oddity they did find and make work is that the high idle in the cab works only in neutral with the park brake set. When active it does not set a high idle at a preset RPM but it does give control to the governor on the pump panel. To increase the idle the you have to go to the panel and increase it with the governor. Just seems strange and I don't remember how it worked before this.

    Yes the transmission indicator does show drive when in pump gear. I think it reads 4-4? sound right?

    Any idea what interlocks the engine requires? What each pin does on the engine ecm connector does?

    Basically what does the Engine ECM need to accept the throttle control from the governor?? should the voltage be on pin 30 or 36??

    We are at a loss and need this truck back in service.

    thanks
    Last edited by spuddy98; 07-16-2014 at 11:16 PM.
    prepare for the worst<br />Hope for the best


  2. #2
    Forum Member islandfire03's Avatar
    Join Date
    Oct 2006
    Posts
    2,566

    Default

    Did it previously work fine and then just started working this way?

    Just an off the wall thought. go through the harness and check ALL the grounds from chassis to body. They are very important in making things co-operate, especially electronics.
    Is it hard wired or multiplexed?

    chassis high idle should only work with park brake set and in neutral unless over ridden by the class 1 when in pump gear.
    Last edited by islandfire03; 07-17-2014 at 08:33 AM.

  3. #3
    Forum Member
    Join Date
    Apr 2004
    Location
    Bossier Parrish, Louisiana
    Posts
    10,557

    Default

    It's a Pierce .... You must be mistaken about ANY malfunction.
    SFD_E73_RET likes this.
    Train to fight the fires you fight.

  4. #4
    Forum Member
    Join Date
    Jan 2002
    Location
    Jamestown NY
    Posts
    28

    Default

    It worked on day. Next day didn't. It's at a local navistar garage now. Just talked to the tech and he says he fauns a problem with a signal from the transmission. He says it goes from transmission to a relay to the PMC and to the engine ECM.
    It is hard wired.
    He did check every wire connection he could find. The labor bill is huge.

  5. #5
    Forum Member
    Join Date
    Jan 2002
    Location
    Jamestown NY
    Posts
    28

    Default

    LA fire educator: it's a pierce? Our small department has 5 pierce apparatus (3 engine 2 - 100' ladders) that's out of 7 firefighting apparatus. Our most recent purchase was a 4Guys engine built on a Spartan chassis. Was an honest competitive bid award. Spartan ERV missed by a couple hundred bucks and pierce was 10s of thousands beyond those two. Way too many issues with pierce to consider myself "happy" with the truck or their service.

  6. #6
    Forum Member
    Join Date
    Jan 2002
    Location
    Jamestown NY
    Posts
    28

    Default

    really? only one reply and its a question?
    prepare for the worst<br />Hope for the best

  7. #7
    Forum Member Bones42's Avatar
    Join Date
    Mar 2001
    Location
    Pt. Beach, NJ
    Posts
    10,672

    Default

    Not much to say. It would go back to the dealer until the issue is resolved.
    "This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?

  8. #8
    Forum Member
    Join Date
    Apr 2004
    Location
    Bossier Parrish, Louisiana
    Posts
    10,557

    Default

    Quote Originally Posted by Bones42 View Post
    Not much to say. It would go back to the dealer until the issue is resolved.
    And more than likely it will turn out to be electronic or computer-chip based.

    Man, I just love today's vehicles.
    Train to fight the fires you fight.

  9. #9
    Forum Member
    Join Date
    Nov 2002
    Posts
    1,132

    Default

    Probably the biggest problem is trying to make a fire truck out of a Navistar

  10. #10
    Forum Member
    Join Date
    Nov 2007
    Posts
    585

    Default

    In order for the governor to obtain control of the throttle it requires a signal from the pump shift circuit. Since the pump is actually shifting and the transmission is going into 1:1 lockup, it appears that either the governor is not getting the signal or it is not responding.

    Get the wiring diagram of the governor and find the correct input and test it for voltage while performing a shift sequence. No signal, the problem is from the signal circuit. If there is a signal the governor needs looked at.

    As previously stated, grounds should always be checked. They can cause replacement of expensive items for no reason other than frustration.

  11. #11
    Forum Member islandfire03's Avatar
    Join Date
    Oct 2006
    Posts
    2,566

    Default

    Quote Originally Posted by Bones42 View Post
    Not much to say. It would go back to the dealer until the issue is resolved.
    It's a 1999 pierce / Hayrake. 15 years of use / abuse and normal wear & tear. Grounds corrode, multi pin electrical connectors get corroded or sloppy, & parts wear out.
    Start with the easy & work up the checklist.

  12. #12
    Forum Member Bones42's Avatar
    Join Date
    Mar 2001
    Location
    Pt. Beach, NJ
    Posts
    10,672

    Default

    Even at 20 years old, if it's not pumping correctly, it's going to the dealer to get fixed. A non-functioning truck is of no value to me. It needs to be fixed quickly and correctly. If you don't have a dealer that will service the trucks after that time span, I feel for you. Our dealer services and supports the trucks for their lifetime.
    "This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?

  13. #13
    Forum Member
    Join Date
    Oct 2008
    Posts
    27

    Default

    This is when having a sister truck is very helpful.. You're saying the governor is sending the proper info and it's making it to the ECU, but it's not responding?

    I would look for park brake interlock on the scan tool. You can have the light on the dash working, but I have seen trucks that have two separate switches, and when the other fails it's not so obvious. Also make sure the idle validation switch is functioning. (seen in data display on a scan tool)
    If you can't fix it with a hammer, you have an electrical problem.

  14. #14
    MembersZone Subscriber
    Join Date
    Apr 2009
    Location
    SW Missouri
    Posts
    1,153

    Default

    Quote Originally Posted by Cutlass84 View Post
    This is when having a sister truck is very helpful.. You're saying the governor is sending the proper info and it's making it to the ECU, but it's not responding?

    I would look for park brake interlock on the scan tool. You can have the light on the dash working, but I have seen trucks that have two separate switches, and when the other fails it's not so obvious. Also make sure the idle validation switch is functioning. (seen in data display on a scan tool)
    Along that line of thought....If the switch on the transfer case is not working and giving you the 'ok to pump light' it might not be giving the governor control of the throttle.

  15. #15
    Forum Member
    Join Date
    Jan 2012
    Location
    New Jersey
    Posts
    252

    Default

    We have a Seagrave pumper that has a DD 6v92 motor that was having all kinds of problems, so a new computer was installed and the truck runs great now!

  16. #16
    Forum Member
    Join Date
    Nov 2007
    Posts
    585

    Default

    Quote Originally Posted by rm1524 View Post
    Along that line of thought....If the switch on the transfer case is not working and giving you the 'ok to pump light' it might not be giving the governor control of the throttle.
    If the switch from the transfer case were not working, the transmission would not go into fourth gear lockup as indicated in a previous post.

    Again, check for input at the governor, it is the last in line to get informed. Everything else in the interlock sequence has to happen before the governor can control the circuit. Then work backward to find the fault. Basic stuff.

    Before the transmission can even go to lockup; the park brake must be set, transmission shifted to neutral, pump engaged, transfer case or PTO engaged, if a transfer case is involved a signal gets sent to the transmission to obtain a 1:1 gear ratio, i.e. 4th gear in nearly all Allison transmissions. All of that has happened or the transmission readout would not indicate lockup.

    That just doesn't leave a lot of stuff to check.

    Go to a professional.

  17. #17
    Forum Member Johngagemn's Avatar
    Join Date
    Jun 2004
    Location
    Woodbury, MN
    Posts
    91

    Default

    Quote Originally Posted by firepundit View Post
    If the switch from the transfer case were not working, the transmission would not go into fourth gear lockup as indicated in a previous post.

    Again, check for input at the governor, it is the last in line to get informed. Everything else in the interlock sequence has to happen before the governor can control the circuit. Then work backward to find the fault. Basic stuff.

    Before the transmission can even go to lockup; the park brake must be set, transmission shifted to neutral, pump engaged, transfer case or PTO engaged, if a transfer case is involved a signal gets sent to the transmission to obtain a 1:1 gear ratio, i.e. 4th gear in nearly all Allison transmissions. All of that has happened or the transmission readout would not indicate lockup.

    That just doesn't leave a lot of stuff to check.

    Go to a professional.
    Actually the switch at the transfer case does not always control the 4th gear lockup request. With an electric shift this signal usually comes from the "pump" side of the shift switch in the cab, or is tied in between there and the electric shift unit on the transfer case. In the case of an all air shift, there will usually be an in-line air pressure switch on the "pump" air circuit. This avoids mis-shifts and not getting lockup if you have a butt-tooth shift occur initially in the transfer case.

    Things to check:

    1. Are your "Pump engaged" and "OK to Pump" lights, as well as your "Throttle Ready" light at the panel working?

    If no, test the switch indicating switch on the transfer case. If yes:

    2. Are any other gauges/controls that only become active when the pump is engaged functioning or are they down as well?

    If yes: likely an issue with the governor itself. If no, you have an interlock failure of some variety.

    3. Are you positive that the pump is actually engaging properly? Has anyone verified rotation of the impeller shaft of the pump (not the driveline shaft)?

    If no, try shifting manually, or whatever is necessary to correct the pump transmission shift problem (possible overhaul required). If yes, now we have to start digging into wiring.

    4. Check for input to the activation control wire for the governor system. Is there is a proper signal present when the pump is in gear?

    If yes, the problem is likely in the governor itself, if no, again points to an interlock failure.

    5. Check return signal from automatic transmission control module that confirms lockup, check brake interlock signal, check for proper function of the Pierce control system (have to call the boys at the plant for that), etc.

    That's the best stuff to start with and will point you to the culprit.
    Just a guy...

    Lieutenant - Woodbury, MN FD (Retired)
    Road Captain - Red Knights MC, MN4

    Disclaimer: The facts and opinions expressed above are mine, and mine alone, and are not intended to represent the views of any company I have ever worked for, past or present.

  18. #18
    Forum Member
    Join Date
    Nov 2007
    Posts
    585

    Default

    Quote Originally Posted by Johngagemn View Post
    Actually the switch at the transfer case does not always control the 4th gear lockup request. With an electric shift this signal usually comes from the "pump" side of the shift switch in the cab, or is tied in between there and the electric shift unit on the transfer case. In the case of an all air shift, there will usually be an in-line air pressure switch on the "pump" air circuit. This avoids mis-shifts and not getting lockup if you have a butt-tooth shift occur initially in the transfer case.
    I didn't say the pump switch "controls" the sequence. I pointed out that it is only one of the things that must occur prior to 4th gear lockup on an Allison transmission if the unit is wired correctly. No competent person would rely on a signal from a dash switch to say the transmission is in gear when there is a mechanical switch on the pump that will only activate if the pump shift is complete.

    If it is wired using anything else to indicate pump shift it is not wired per manufacturer's recommendations.

    Either way, the poster indicated lockup had occurred. That means the parking brake signal has been received, the pump indicates it has shifted into pump gear, and the transmission is signalling lockup. What is left is receiving that signal from the transmission and, using a relay, getting that info to the governor.

    If there is a signal to the governor on the appropriate input, the governor is at fault. If there is no signal it lies between the governor and that signal from the transmission. Your number 4 step should be number one in this case.

    It isn't the park brake or the transmission would not be reading 4:4. The park brake signal must be received to activate lockup.

  19. #19
    Forum Member
    Join Date
    Nov 2007
    Posts
    585

    Default

    Quote Originally Posted by Johngagemn View Post
    Actually the switch at the transfer case does not always control the 4th gear lockup request. With an electric shift this signal usually comes from the "pump" side of the shift switch in the cab, or is tied in between there and the electric shift unit on the transfer case. In the case of an all air shift, there will usually be an in-line air pressure switch on the "pump" air circuit. This avoids mis-shifts and not getting lockup if you have a butt-tooth shift occur initially in the transfer case.

    Things to check:

    1. Are your "Pump engaged" and "OK to Pump" lights, as well as your "Throttle Ready" light at the panel working?

    If no, test the switch indicating switch on the transfer case. If yes:
    So, even in your post about how the switch on the transfer case doesn't control the lockup procedure, your first step is to check the switch on the transfer case.

    Really would like to hear more about those systems that ignore that little switch.

    Just sayin'

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Replacing pump panel throttle
    By aalexander605 in forum Firefighters Forum
    Replies: 5
    Last Post: 05-27-2011, 03:20 AM
  2. Pierce Pumpers Throttle and pump issues
    By fd20man in forum Apparatus Innovation
    Replies: 9
    Last Post: 04-08-2011, 03:50 PM
  3. Pierce Crash Test Failure
    By MackBulldog in forum Apparatus Innovation
    Replies: 0
    Last Post: 11-15-2008, 04:33 PM
  4. Pierce Aerial failure??????
    By UFDFF15 in forum Apparatus Innovation
    Replies: 196
    Last Post: 05-08-2007, 07:49 PM
  5. Pierce Failure
    By ff43065 in forum Apparatus Innovation
    Replies: 25
    Last Post: 08-07-2005, 02:50 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts