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Thread: Pierce Throttle up in pump gear failure

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    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; 07-17-2014 at 12:16 AM.
    prepare for the worst<br />Hope for the best

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    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 09:33 AM.

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    It's a Pierce .... You must be mistaken about ANY malfunction.
    SFD_E73_RET likes this.
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    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.

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    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.

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

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    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?

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    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.

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

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    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.

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    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.

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    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?

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    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.

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    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.

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    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!

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    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.

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    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.

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    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.

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    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'

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    Quote Originally Posted by firepundit View Post
    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'
    If you actually read the full text I wrote I went through a litany of issues that could be occurring. It is entirely possible to get the pump in gear and operating in 4th gear lockup with the shift indicating switch on the pump transfer case not functioning, depending on how the OEM wired the lockup circuit. Virtually every apparatus builder uses that switch as only a secondary means of requesting pump mode from the automatic transmission. The primary method is either the "pump" side of the switch in the cab for an electric or electric-over-air shift mechanism or via an air pressure sensor on the "pump" air circuit on a completely pneumatic system.

    Your assumptions about the instructions provided for wiring from the pump manufacturer are also incorrect. Those wiring diagrams are intentionally vague as the pump manufacturers know that various apparatus OEMs have different methods of setting up their ESCIS (Engine Speed Control Interlock System). They give a basic explanation of what is what and show the components being wired to a magic box called "ESCIS". It's up to the OEM to figure out/decide how to make that all jibe with their wiring or multiplex system. As long as it meets NFPA 1901 safety requirements for system operation it's considered good.

    While there are certain OEMs that for a short while wired the lockup request directly to the signal from the pump shift indicating switch, that's a relatively rare thing. Based on the age and manufacturer it is highly unlikely to be wired that way, as Pierce knew better than to rely solely on that switch for lockup request in 1999.

    Back when virtually every pump shift was electric the OEMs pretty universally used the cab switch for the pump shift to activate the lockup request. It was when air shifts started becoming prevalent that it threw a hitch into the giddy-up. Some manufacturers would employ an electrically controlled air solenoid valve to operate the air shift so that they could keep all of their wiring the same. Those systems were notoriously unreliable so most manufacturers moved away from them quickly and went to the simple Williams air control valves still in use on most apparatus built today. They realized that installing a low pressure air pressure switch would accomplish the same thing.

    If you question where my knowledge comes from, it is from working for a major pump manufacturer for 12+ years providing tech help, service, and training. If you would like further citation, I am the author of the pump shift troubleshooting document used by the same company.

    Just sayin'

    Edit to add:
    The point of the story is: you can get 4th gear lockup with the shift indicating switch inoperable, broken, or even removed from the truck. You may not, however, get interlock release for pump panel controls, such as an electronic pressure governor. I recommended they check the switch because of the specific problem they are having, not because it affects lockup.
    Last edited by Johngagemn; 10-14-2014 at 03:33 AM.
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    All pump shifts used to be electric? I don't think so. Air or levers were most prevalent until Waterous came out with an electric shift. Post the part number for a Hale or Darley electric pump shift from "back in the day."

    Look, it is this simple. If you have found an apparatus equipped with a split-shaft transmission that can get fourth gear lockup without the pump shift indicator switch working the builder did not wire the unit per NFPA 1901, Allison instructions, or the pump builder's instructions. You can fantasize all you want to but, that is a fact. Take your diatribe to the EVS forums and ask there if you don't believe me.

    On units prior to 1991, NFPA doesn't apply since they didn't address the issue until then. They addressed it due to a rash of run-away apparatus from improperly installed systems. However, that was before the electronic World Transmission when the lockup was a couple of solenoid valves on the side of the transmission. Still, pumps had the switch and recommended its use even back then. If the builder didn't use it they did so against the manufacturer's recommendations.

    Also, having wired a few of these things myself, I have never found the instructions to be vague.

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    Please don't try to put words in my mouth. I said when *virtually* all pump shifts were electric, which they were from the early 70's up through the late 90s. And the electric shifts were around prior to that too, although a manual shift was more prevalent in the 50s and there was a pretty good mix in the 60s.

    If every rig that can get 4th gear lockup without the pump transmission switch is non-NFPA compliant than you better take 80% of the rigs on the road out of service. Sending a lockup signal to the input wire on the Allison TCU is not the same thing as disabling the safety interlock for panel controls. NFPA doesn't say you have to have confirmation that the pump is in gear for 4th gear lockup, it says you have to have it for interlock release of panel controls. Those are two completely separate animals.

    The runaway apparatus issues from prior to '91 had less to do with improper installation and more to do with operator error or paying attention issues. The problem stemmed from the fact that on most rigs of that era you had a live mechanical throttle cable operable at the pump panel. If the operator failed to verify that the pump transfer case was, in fact, in pump, and then put the tranny into drive, you had a live throttle at the panel with a driveable truck sitting in first gear. Operator goes to the panel and cranks up the throttle, and then all Hell breaks loose.

    On the pre-91 systems the switch was primarily only used to tell the operator whether or not the pump transmission had completed the shift. A red light indicated a failed shift or a butt-tooth, a green light meant it had shifted to pump. Some OEMs took the power for the solenoid valves from that switch, but most were set up with the primary activation being from the same terminal of the SPDT cab shift activation switch that was wired to move the shift unit to the pump position.

    The reason on newer trucks is simple: with an electronically controlled transmission if you with the 4th gear request only to the shift indicating switch then you won't get 4th gear lockup to occur if you get a butt-tooth shift. The operator will have to go to Drive to finish the shift, then go back to Neutral, and then shift back to Drive again to get lockup. A PITA and not something most firefighters want to deal with, especially when they're still half asleep on a 3 AM call.

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    Quote Originally Posted by Johngagemn View Post
    NFPA doesn't say you have to have confirmation that the pump is in gear for 4th gear lockup, it says you have to have it for interlock release of panel controls. Those are two completely separate animals.
    Oh, let's see. NFPA requires "A 'Pump Engaged' indicator shall be provided in the driving compartment to indicate that the pump shift process has been successfully completed." Note that it does not say that the pump operator flipped a switch or tried to engage the pump in some manner. it explicitly says, "has been successfully completed."

    Oh, and then they require, "An 'OK To Pump' indicator shall be provided in the driving compartment to indicate that the pump is engaged, the chassis transmission is in pump gear, and the parking brake is engaged."

    Clearly you do not have a clue what you are talking about. That is evident when you claim that virtually all pump shifts are electric. Call Hale or Darley and ask for an electric pump shift repair kit and see what they say.

    Oh, that 80% figure is a load of bull as well.

    I seriously hope you do not work on fire apparatus for a living.

    I tried my best to be civil in this post however, I am not fond of being "corrected" by someone who doesn't have a clue about the topic but tries to sound like an expert. The interlock system is an important safety feature that lives literally depend on. Do yourself a favor and don't give anymore advice until you know a little more about the subject.
    Last edited by firepundit; 10-16-2014 at 01:08 PM.

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    Quote Originally Posted by firepundit View Post
    I tried my best to be civil in this post however, I am not fond of being "corrected" by someone who doesn't have a clue about the topic but tries to sound like an expert.
    Johngagemn is actually one of the ones that I do consider to be a subject matter experts on this topic in particular...he's provided me some very timely and accurate information in the past with some planned pump purchases. He's far more involved in the industry than I believe many might be aware.
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    Quote Originally Posted by BoxAlarm187 View Post
    Johngagemn is actually one of the ones that I do consider to be a subject matter experts on this topic in particular...he's provided me some very timely and accurate information in the past with some planned pump purchases. He's far more involved in the industry than I believe many might be aware.
    He sure missed the boat on this one.

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