1. #1
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    Talking Engine Com Lost message will not go away!

    Alright boys and girls, I have a problem that has been frustrating my crew and the crews on the other shifts for the past six months. I drive a 2000 Pierce 75' quint. We keep getting an alarm activation on our display panel stating "engine com lost". We have taken it to the shop on various occassions and each time they hook up the diagnostic tool it shows no problems. The mechanic somehow resets the system and we are good for maybe a week and then the alarm comes on again. I have talked to other companies who have the same rig and they have not had any problems. Some of the theories that have been floated are as follows: water in the engine compartment (during dry spells we still had the alarm go off), overcharging of the batteries (i'm skeptical about this one, doesn't the system do a trickle charge when plugged in to the shore line?), compartments are dirty and as such the sensors get dirty. We are at our wits end, I am getting ready to tear open the dash and cut the wire to the audible alarm. What's worse is that when this alarm comes on the throttle on the pump panel will not work. I'm worried that at a fire I'm gonna have to put a brick on the gas pedal just to increase the pressure for the lines. Any help will be greatly appreciated.....

    Thanks,

    Ruben
    El Paso Fire Dept.
    Q18 c shift

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    I am not an apparatus mechanic but here are a couple of things to consider.

    The term "Engine Com Lost" seems to indicate that there has been a failure of the "computer" system on the truck. It is going into a fail mode which allows you to drive the truck but not operate the throttle on the pump panel.

    This could be caused by any number of things from a bad ground to defective sensors, relays,etc.

    Has the apparatus been taken to the shop immediately after one of the incidents without turning off the master switch? Turning off the master switch in most cases has the same effect as disconnecting the batteries. This cuts power to the computer thus erasing any trouble codes stored.

    Cutting the wire to the audible alarm probably will only silence the alarm. It won't help with the problem of the throttle at the pump panel being inop.


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  3. #3
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    Ray,

    We have taken it to the shop immediately when the alarm goes off and as usual by the time we get there the system reverts to normal. They put their diagnostic machine and it reads everything okay. They have told us that if the engine com lost comes on while pumping that pushing the load manager button should allow us to throttle. Have tried this and it has not worked. I agree that this seems to be more a problem with the rigs computer. Turning off the master switch doesn't fix or reset it either. We've tried that. I'm hoping that someone else has had the same problem and could offer a solution. It is an intermittent problem that I am afraid is going to hit at the worse possible time. Thanks for the reply....

    Rubizzle

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    I would start checking at the batteries. look and see if there is possibly a ground wire that has come loose from the battery. also check about the drivers and capts seats for a ground wire for the transmission computer. i have heard of them placing the ground for the ecu in this area and it is not making good contact. what does the transmission do when this happens. does it shift ok or lock into one gear. does it give you any flashing codes. i am guessing that you have an allison transmission but unsure of the engine type. you can check the codes in the trans from the shifter pad. email me at firetruckfixer@cox.net and ill walk you through it. if you are loosing com links this is data transmission lines on the 1587 or 1900 group of wires. again engine type would be helpful. jeff

  5. #5
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    Have you tried contacting the Pierce dealer in that area? They may have run in to the same problem before. I believe the dealer in that area is either First In Apparatus or Martin's Apparatus.
    Just a suggestion...

  6. #6
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    Default Re: Engine Com Lost message will not go away!

    Originally posted by RubenL24
    I drive a 2000 Pierce 75' quint.
    Well there's you problem right off!

    Sorry, couldn't resist, seriously, I would suspect a loose connection or bad wire in one of the myriad of wires which run your truck. Vibrations make it come and go so unless you just happen to have it occur while the diagnostic computer is hooked up the techs will never find it. Dirt in the compartments should not be a problem. Water could be if the wire's insulation or the connector in question was exposed to it.

    I'd get out one day and crawl all around the truck while it was running and shake every wire and check every connector (pull it apart and put back together, but not while its running). I'd focus on the wires in the engine compartment and the computer first (usually decent sized bundles). Also look at the wiring going to the engine controls on the pump panel. You may be able to find the exact wire or connector causing the problems.

    2000, I'm guessing its no longer under warrenty, but you should still try to twist the arm of your local rep a little, after all you will eventually buy another truck and I'm sure they would not want to be excluded from the bid process due to a back track record. If the local rep does not want to help contact Pierce directly and speak to someone with "VP" in their job title.

    You're also absolutely right about this happening on the fire ground, this truck should be removed from service until the problem is both discovered and corrected.
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  7. #7
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    Default Re: Engine Com Lost message will not go away!

    Originally posted by RubenL24
    I'm worried that at a fire I'm gonna have to put a brick on the gas pedal just to increase the pressure for the lines.
    That shouldn't work either, as when you engage the pump the accelerator pedal is electronically locked-out.

    Remember that even though you've got a traditional looking pedal, it's still an electronic throttle.

    I think I've read about some departments spec'ing backup throttles... not sure how those work, but I think they're just backup electronics.
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  8. #8
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    Comm. lost means that a sensor,or panel to the Engine control computer has lost continuity.These are bi-directional units that sent and recieve information constantly.Places to look for problems:Pump control panel(electronic govenor)any bulkhead connectors/plugins between there and the engine computer.Powers and grounds to both the controller,transmission,and computer.Any connectors or plugs that lead to an electrically shifted transmission.My guess would be a bad pin or wire in one of the connectors leading to the pump govenor but I'll bet you will find it in ONE of the connectors.When you do please post results as it might help someone else out. T.C.

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