Yes the horn blowing after doing the pedal dance was just a coincidence.
And so the horn blowing was due to having the key switch on for an extended time without oil pressure present while you waited for the codes to be revealed by the MIL blinks.
Key on/engine off time exceeded the alarm system timer which permits a grace period before alarm sets. If oil pressure is not detected after the grace period has elapsed, it sounds the alarm (and hopefully also shuts off the ignition to stop the engine).
Got it fixed. Spoke to a few Komatsu dealers and found that the delay is inherent in all IC Komatsu forklift trucks.
The problem causing the truck to be in limp mode was when we took off the control valve cover to replace the gasket we needed to unhook the accelerator linkage and in doing so it messed up the accelerator pot. We recalibrated the pot and all is fine.
Maybe we should have a forum dedicated to inherent problems that can't be fixed in particular make or model trucks. I can think of a few......
Possible that the tranny overheat sensor wire is grounding out or the speed sensor circuit. Also as mentioned above check for overheat and oil pressure.
What engine is in this unit?
This truck is equipped with an "Engine Check" alarm made by Indo Tech. I don't know if it is standard equipment or not. As I said, when we do the pedal dance the horn sounds and the display lights shut off.
So we can't address the transmission issue until we find what is causing the truck to be in Limp mode and what the code is.
I assume if I buy the 3EA-55-38680 cable then I can read any of the codes with a OBDII. Does anyone have one of these cables?
The earliest production FGxxST-14 models did not get the operator presence system, so if you don't see a hole in the hood, it is one of the few earliest ones.
Unless this truck has had some kind of modification (think...improper) to tie the OEM horn to some kind of alarm set up, like low oil or high coolant temp.....there is really no reason for the horn to react at all to the key switch.
I have seen some low oil/high temp systems that do utilize the OEM horn as an alarm by adding a grounding relay to the horn ground circuit (much the same as adding an extra horn button on the dash).
We still have this issue but another one came up and there's a possibility that they are related.
Mil light is on on truck is in Limp mode. Performed the pedal dance to try to get the code and the dash lights go out and the horn blows until the key is turned off.
I've read that this model is equipped with the operator precence system but there are no wires going to the seat and there isn't a hole in the hood for wires to pass through anyway.
We checked the strainer and it was clean. We will replace the control valve gasket and advise.
I doubt that putting air pressure into the main oil circuit would give accurate results.
I can imagine that there is a "normal" amount of leakage at various locations in the control valve under any conditions.
This normal leakage would obscure any leakage that might be escaping at a failed gasket surrounding the mail oil gallery where the trans case meets the control valve.
A more accurate test would be to put an oil pressure gauge into the main test port and see how much oil pressure is present at idle RPM and then at 2,000 rpm.
Ideal oil pressure would be near 150 PSI at 2,000 RPM. The absolute lowest pressure at idle ought to be something higher than about 90-95 PSI or so.
If you are seeing main oil pressure less than 90 PSI at idle when the truck is thoroughly warmed up, then you likely have a breach in the control valve mounting gasket.
One more thing you might want to do (in the form maintenance) is to check and replace the suction strainer.
It occurred to me that if the suction strainer is beginning to collect debris, it might be starving the pump on cold start ups and oil output would be reduced until the pump regains its internal pressure head. And of course, that would be worsened if the control valve gasket was failed.
Suction strainer is on the right hand side of trans case behind a 4 bolt cover plate.
Strainer part # AS35303-3601, cover O-ring # AS55931-3660.
If I put air pressure to a port on the control valve and no air escapes around the gasket wouldn't that prove that the gasket is intact?
GREAT answer L1ftmech. I have seen a few of these but not enough of a problem that the customer want to fix. Its good to know where to start. Thanks
You know how they say use oem filters because the have a check valve built in to keep pressure, I don't know if that would apply here
I've seen this problem on a older Clark. The trans pump is losing it's prime after sitting for a day or so. That gasket that L1ftmech mentions may well be the problem.
Not exactly normal. I have had a fair share of control valve mounting gaskets to "blow out" at the main pressure oil gallery feeding into the control valve assembly. When the gasket blows out, it often loses a section of gasket and the breach simply sprays oil back into the transmission case/sump, so you never know it has happened until the truck begins to act up.
And your description about the 5 second delay is not exactly how failure of that gasket usually causes the truck to behave.
Failure of the gasket as I described usually causes the transmission to have a hesitation before beginning to move when the accelerator pedal is pressed down. The hesitation occurs every time the truck stops and is asked to move again, until the gasket is replaced.
I wonder if the 5 second delay you are seeing might also be an indicator of an early stage of the gasket blowing out in that it could be allowing the gallery above the pump to "siphon" or drain itself empty when the truck remains parked for a long period.
I will PM you a photo of a failed gasket on one of these trucks.
Our fix to prevent future blowouts has been to use an automatic center punch and put a circle of punch marks about 3/16" apart around the mail oil gallery on the aluminum control valve body. The pin punch marks are just enough upset to grip the gasket and keep it from blowing out due to the "balloon effect".