hello, can you please tell me what model of HITACHI OBDII SCANNER you are working with?...this is my story...we are having problems working on a NISSAN with a K25 engine. it arrived not starting showing a P03 code. i was told this was an ECM issue with communication. we replaced the ECM and the truck started and seemed to run fine. the code did not how up anymore. it then started to have issues with the fuel system. after troubleshooting that we replaced LP gas converter diaphragms and filter. all seemed to work fine. however, once we delivered the forklift to the customer a day later the code E23 appeared again. the forklift starts and runs but does not have acceleration. do you have any ideas?

thanks,
Jay

thanks
Jay

Well, my earlier statement may have been a generalized WAG, sort of.
It's danged hard sometimes to remember everything you read in a manual, but I went and looked at the Komatsu publication service manuals for the K-21/25 and it essentially says that safe mode for overheat is initiated at 1,000 RPM once the ECU determines that the engine is actually overheating.
The 1,000 RPM "sound" is very close to the rated 750 RPM idle speed, so in the few cases where I have actually caught one in limp mode, I may have just considered that to be "idle speed" or even maybe a "fast idle".
The manuals further describe that a malfunction in the MIL system itself will limit engine RPM to a max of 1,500.
I did experience that once when the K-21 engine was still fairly new to us. I wondered why the engine would not run at full RPM and why if there was something wrong......the MIL was not showing a code. It turned out that the MIL did not light up during self check either and that led me to check the MIL bulb, which was defective. But that truck had been sent to us for that reason (not run right) and when I discovered the burned out MIL bulb, I also found that the cavity above the MIL bulb had been obscured with electrical tape.
I guess that somebody had gotten tired of that MIL staying lit all the time and since they lacked the ability to fix the cause, they simply "put a gag" on the messenger so the operator would not know the light was on. I guess the bulb finally failed from staying lit all the time and that was when the truck began to limp.

I am willing to bet that Dash 14 Komatsus with K-21 will shut down to idle only when step 2 overheat is still present" is not entirely accurate, although it seems a valid observation, but step 1 overheats still slow the motor, just not enough to really notice (max RPM about 2300 RPM step 1 overheat cuts it back to 1700 or so, just making up the numbers, I didn't bother to look them up, but it is close). thing is, unless you have a long run, you might not ever get above 1700 rpm in usual operation enough to notice.
But the [real] point about self resetting limp home when the motor is cool is accurate.

Thanks swoop. I will be sure to inspect the t-stat and the sensor for any signs of deposits and gunk/goo as well as trying for a sighting of the exposed radiator cross tube when I dump the coolant for the repairs.
I have to wonder about how specific OEMs request ECU parameters be set up for their application when the choose an engine for their build.
I know from experience that the Dash 14 Komatsus with K-21 will shut down to idle only when step 2 overheat is still present (though events over heat step 1 and step 2 will be recorded in ECU memory).
I'm getting a visual (in my imagination) of this mechanic fumbling around on the overheated engine idling in safe mode trying to figure out why it won't throttle up.............while the radiator overflow hose is venting into the hood insulation. Well, you get my drift I'm sure.

yep... even though it did not have any active codes i have seen sometimes certain codes like the stage II overheat put the truck in limp mode or even shut it down and wouldn't let the truck return to normal operation till it was reset, at least on the mcfa trucks. Not sure about the nissan ones, i'm sure they are very similar.
Missing reservoir bottle?
yeah it sounds like some shade tree work to me too...
maybe the operator saw it leaking or cracked and just took it off... who knows ;o)

Anyways about that radiator and hose stuck in the hood insulation... check inside the radiator real close and make sure its not gunked up with that red brown looking gunk that builds up from mixing different types of coolant... also look inside that reservoir hose for the same condition. When you change out that temp sensor if its located at the bypass inlet on the backside of the water-pump on the alternator side, check that bypass hose fitting inside and make sure its clear and not gunked up.
Those are some trouble areas i've ran into in the past where clogging occurs from muddy jelly coolant buildup from mixing wrong coolant types together. And of course make sure the flu's are clear inside and out and you have good circulation in the radiator.

good luck

Yeah, I made a list of the codes I found (using our Hitachi OBD II reader) and then checked the "real time DTC" area and it showed no active conditions still exist.
The truck had actually returned to normal operation (would throttle up OK) when it arrived here.
I cleared all the codes from memory with the Hitachi and then ran the truck for more than an hour, it ran fine and set no codes in that time.
I am going to replace the engine thermostat and temperature sensor arbitrarily just because I can't get any kind of confirmation that an actual overheat event really took place.
The radiator itself was completely full of coolant when the truck arrived here, and being that full suggests that the coolant had been "topped off" very recently. The coolant recovery reservoir is missing from the truck.
Considering that the coolant recovery reservoir is missing and the end of the recovery hose from the radiator was stuffed up into the hood insulation sort of screams "non mechanic" to me.
I have inspected all the wiring at/near sensors and other connectors and all appear to be sound.
After we finish all the repairs I will try to arrange for the truck to be used in regular service for at least a few days here at our dock before sending it home. That way I still have it held captive and will be able to get daily reports of its behavior and will connect the Hitachi to scan for codes before I turn it loose.

L1ftmech,
just remember these codes will have to be cleared out of the ECM in some cases before the engine will return to normal operating mode. Otherwise the 'limp mode' will persist.
I would clear the codes... then....
if any reappear troubleshoot them and repair the problem associated with the code...
then clear them again till you get an 'all clear' no code set condition.
Then the truck should run correctly.
Note: some of these codes cannot be cleared using the pedal dance routine, they have to be cleared using the software diagnostic program.

that stage 2 overheat code has to be cleared from ECM memory once set and i definatly would find out why it was set to begin with and resolve that issue.

And yeah, sometimes you do get tech's that don't know the truck their working on and its just about impossible to get them to admit it probably because they don't want to look bad even though thier actions scream that very thing. DOH!

good luck

The truck had a laundry list of codes stored in the ECU memory.
Only 2 of the codes (overheat step 1 & overheat step 2) were actually due to a real condition with the truck.
All the other codes were pertaining to ETC, fuel injector, and fuel pressure..........were set by the mechanic who was trying in vain to solve the supposed problem of why the truck would only idle, not having a clue about the ECU putting the engine into "safe mode".
I found plenty of evidence that the truck probably did suffer an overheat event, but the people at the other location are not admitting to anything along that line.
While we have the truck, we are going to do some other much needed repair work as well.

Check around the ETC for shorted or broken wires. Clear code if it will clear and if it does, gently wiggle the harness where the ETC wiring joins back in in the harness. The e33 code displayed will let the truck only idle as it is an step 2 overheat mode.

from the Cat code list:

E23 Throttle sensor error signal
E33 Overheat step 2 (E32 is overheat step 1)

yep, and you hit on one of those spots where I can tell if someone doing an "OSHA compliance inspection" is really a salesperson or really doing OSHA mandated inspection work.
As I read it, the regulation seems to say that the operators manual MUST be -available- to the operator, but does not specify where it must be, (on aerial lifts, the regulation is pretty clear that the truck must not be operated unless the manual is in the operators compartment on the _platform_). When I hear it must be in the seat back and the customer must buy a new seat with a place for the manual, I know they are being -sold- something, other than OSHA compliance.

Thanks Edward. I have some doubts about there even being an owner's manual present with the truck when it arrives here.
Forklift operators have little or no interest in said manual and will throw them in the trash can.
For that reason, management sometimes resorts to keeping a copy of the manual on file in the office, or they don't have a copy at all.

the nissan and MCFA product should be the same codes of the tier 2 & 3 k21-k25 and you should be able to find a short explanation code list in every MCFA product's operator's manual usually in the seat back. right in the middle, about page 101.