This is a long post, even by my standards, but I want to try and include as much detail in the presentation as possible instead of waiting for respondents to ask a lot of questions, and then have to add details one at a time.
I will outline the problem in the order of occurrence that led me to the present problem.
During the first week of 2013 the truck was sent to our shop from another facility for us to fix a problem indicated by the MIL being lit continuously.
The DTC at that time was 0031, "HEGO sensor heater circuit open".
Testing the O2 sensor heater circuit (in the sensor itself) showed the HEGO to be in good order so I then checked for continuity on the BLUE/black tracer wire from the HEGO chassis connector to pin # 24 of the ECU chassis connector. That showed there was continuity present, so the wire was sound.
My conclusion was that the ECU itself was defective.
I ordered a new ECU from our local Komatsu dealer. I obtained the ECU part number from the Komatsu Parts manual we have on hand. I ordered ECU part # 37B-1DT-3210.
When the new ECU arrived, I was told the part number had been superseded to 23710-FT860.
I installed the new ECU and immediately got an MIL and DTC 1245 described as "LPG FUEL PRESSURE SENSOR HIGH, INPUT FAILURE". But the 0031 HEGO DTC was gone.
Subsequent investigation and conference with the local Komatsu dealer revealed that the ECU I had ordered was configured for the early version K-21 which has the LPG pressure sensor mounted atop the injector body with two 5mm screws. But the ailing K-21 I'm working with has the later version of LPG pressure sensor which threads directly into the front of the injector body. I learned that the ECUs do not interchange so I had no choice but to let my local dealer select the correct ECU by VIN and the Nissan part # from the original ECU (23710-FT81B). We will retain the "wrong ECU" in our stock because we actually have quite a few of the early versions in our fleet.
OK, if you are still reading, we are now going to get to the present problem, and I have not had but about 1 hour to devote to it so far at work, but I am trying hard to cipher it out here at home this weekend.
Friday I got the latest ECU and the old Nissan part number has been superseded to 23710-GU21A.
I installed this ECU and as soon as the engine started, the MIL came on, a few seconds later the engine stopped running. An immediate attempt to restart was futile but after waiting a minute or so it restarted.........and died again after running about 30 seconds. This could be repeated with consistent results.
Connecting the Hitachi diagnostic reader tool revealed the DTC as 1241 "LPG_F/INJ 1 FAILURE (NO INJ MEDIUM ZONE)", further described as "LPG injector signal circuit is open" in our Komatsu SM 300 manual.
Thinking perhaps there might be a compatibility issue with yet the newest ECU I decided to re-install the original ECU and see what happened.
With the original ECU in place, the engine started and immediately lit the MIL, after about 30 seconds the engine died.
Checking the reader revealed DTC 0031 (as expected) and DTC 1241 (same as with the new ECU).
When we received this truck DTC 1241 never came up and we ran the ran the engine for long periods and it never shut down.
I only got as far last evening as determining that the engine is shutting down because the ECU (both of them) is interrupting power to the LPG Interception Valve (fuel inlet solenoid valve). I interpret this action as part of the safety interlocks incorporated into the LPG system design to prevent leakage of LPG through the engine should some parameter (injection signal?) be absent while the key switch is ON.
With the Hitachi reader I was able to watch the indicated LPG pressure drop rapidly from 23 kpa to 1 kpa at which point the engine died. A physical check of the vapor hose at that time showed no fuel pressure present, so I was able to deduce that the engine is consuming the quantity of fuel between the Interception Valve and the Injector, resulting in "fuel out".
Has anyone out there ever had a problem similar to this?
I am suspecting that there might now be a broken wire in the big chassis connector at the ECU and I plan to do continuity testing when I return to work Monday but I wanted to run this issue past the forum community in hopes I might get some helpful feed back.
If you are tired of reading this, imagine how weary I am becoming of this truck.
Showing items 1 - 15 of 16 results.
Truck ran all week doing shop stuff without any problems.
Boss says send it home and he will inform the domicile terminal personnel that if the MIL reappears to inform us immediately.
Unless an MIL or driveability issue arises, this case is closed now.
My boss wants us to use the truck for shop duties this week to see if any DTCs pop up (or other issues). He said if it runs OK all week without a problem we will return it to its domicile terminal on Friday.
Follow up Part 2.
After seeing this I decided I would cut the 2 wires out of the loom and replace them with the salvaged wires. I had about 8" of wire to work with on the salvaged units, so I staggered the cuts of the 2 wires so as to not have a couple of heat shrink tubes adjacent to each other. I did "one wire at a time" and used "strip-twist-solder-heat shrink" method to join and seal the wires. I connected the harness back to the ECU and started the engine. MIL went out after starting and no codes were showing in memory. I taped up the loom and then drove the truck around outside making sure I visited some of the "rougher" areas of pavement for about 20 minutes and so far it has not missed a beat. After the successful test drive I took one of the faulty terminals I snipped from the truck harness and placed it onto a pin from the original ECU I took off the truck. Turned the ECU upside down and the wire just fell off. I extracted another wire from the salvaged ECU connector and repeated the move, this wire stayed in place and would not fall off even when I shook the ECU up and down. Monday I will report my findings to the manager (including the shake demo) and suggest that this truck really should have a new main harness before it is to be considered trustworthy.
This has been a hair pulling "ordeal" in a lot of ways. We received the truck with absolutely no historical information as to problems it may have had, that nobody had ever resolved. There was plenty of reason to think this truck has spent a great deal of down time in somebody's hands, judging from the complete disarray of the truck wiring from front to back. We probably found at least one of the defects that may have been haunting the truck's OPSS (KOPS) system, and that issue may be what ultimately led to all the truck's other issues (except the O2 sensor) with DTCs. This defect that was found was damage to an unused, 3 wire connector near the base of the left rear FOPS pillar. This connector is used to outfit the truck with a "back-up alarm" or a "travel alarm" if the end user wants to have notification that the truck is moving Forward as well as Reverse. The plastic connector body was broken on one side and the BLUE wire was hanging outside the connector. The blue wire here is common to the transmission Forward Solenoid valve and is fed from the Forward Relay. The condition of the metal terminal showed that it had at times been shorting to ground as most of the terminal was eroded away. I suspect that the shorting (even a slight brushing type of short) may have been popping fuses and/or causing false operation of the KOPS system, and fruitless attempts by someone to resolve that issue may have contributed to the damage and destruction to other components in the truck wiring. I can only wonder how many times various connectors (including ECU) had been separated, sometimes by force, in their poking and prodding. But I am near the point of closing this case pending my conference with boss Monday.
Follow up Part 1.
Well, well! As it turns out......the coding of DTCs 1240 and 1241 were caused by a sloppy fitting female receiver terminal at pin #39 in the ECU 81 pin connector of the main wiring harness. DTC 1245 was the result of the same thing at pin #31.
After I checked several things suggested by a senior tech staff member at Komatsu North America and found all those criteria to be OK, it really left no where else to go but to the 81 pin connector.
In my tests I was perplexed that the SST was showing 0 kpa for the LPG pressure sensor and I could not detect the prescribed 2.5 VDC at the sensor connector on the BLUE/black wire that leads to pin #31 at the ECU. I had previously tested all the wiring for continuity and had confirmed there were no open circuits. So I decided to test for 2.5 VDC on this circuit by going directly to the ECU 81 pin connector and testing it "live". This was to be accomplished by inserting a "needle probe" into the back side of the connector body, slipping the needle in between the wire insulation and the connector body till it was in contact with the female receiver terminal. My plan was to observe the SST data screen and test for the prescribed voltage with the engine idling. Voila! With the needle probe pushed in against the terminal.............the fuel pressure on the SST was 27 kpa, and I had the voltage on the VOM. AWRIGHT! I was now able to clear DTC 1245 from the ECU memory but I still had DTC 1241 showing. DTC 1240 was not showing at the time. I studied my notes and charts and proceeded to employ the same technique to other pin positions in the 81 pin connector to see what would take place. I began with the Injector Driver circuit layout and decided I would go from left to right of the Driver wires leading to the ECU. The BLUE wire, pin 39 was first in line. I pushed a needle probe into place and then went directly to the stored DTC screen and cleared DTC 1241. After I started the engine, the MIL was dark, and there were no codes in the ECU memory.
After giving due consideration to this new found data I dug into the bag of connectors and pigtails I salvaged from the other wiring harness R&R job I did in mid-2012. I took that 81 pin connector apart and extracted the wires from pins #31 and #39. I unwrapped the loom at the 81P connector on the truck and extracted wire #31 first. I then took the single wire and manoeuvered it over to the ECU and tested the fit of the receiver terminal to a pin in the ECU and it was so loose that it would rock from side to side. I tested one of the wires I had just taken out of the salvaged 81P connector for fit on a pin and it was nice and snug requiring a slight "pull" to remove it from the pin. I'm splitting this post at this point cause I know it is "over length".
Kevin t, yes. Checking that 5 amp fuse and all the fuses in the engine fuse box was one of my first actions when this stuff began to show up after I installed the first ECU.
Did you check the inline fuse for the injector,there is a fuse on the pigtail connector going to the injector.
I ohmmed the main injector and the assist injector...they are both where they should be, 1 ohm for main injector and 27 ohm for assist injector.
Yes, truck was pressure washed............but we have been to the rodeo many times before. We use due caution and shield the actual ECU connectors by covering them with a hood from an old rain suit, and we make sure not to direct the blast toward the ECU.
Only one of these ECUs has ever been wet at all (that being the original one) but the DTCs are present with both ECUs.
Insofar as any residual moisture in the ECU connectors.... I have seen none at all. The truck was washed on 1/16/13 AFTER the initial ECU was ordered (to correct for DTC 0031).
In trying to establish a "time line" I think it is safe to say that the DTC issue I am having now (along with the spontaneous shut down) surfaced AFTER the washing. But when I washed the truck I did not DRIVE it to the wash bay, I towed it with counterweight removed as we were also replacing the muffler. So I now have no way of telling whether or not these 124X codes might have surfaced as soon as the wetting was done. Forensics after the crime are never as good as having an eye witness.
Having said that, I am also beginning to wonder if the very first DTC (1245) I saw after installing the incorrect, initial ECU may not have been due to a compatibility issue at all, but may very well could have been an erroneous code being generated out of "circuit cross feed noise" in the "now wet" engine harness.
The DTCs I am seeing seem to be stating that there is no fuel pressure and that no injection is taking place. Kinda hard to accept when I'm standing next to a running engine (until it shuts down). The codes appear as soon as the engine starts up, not as a result of the engine shutting down, but vice versa.
I think it is now the time for me to have dialogue with Komatsu USA.
I don't want to cut open a $1,500 harness unless I have no other recourse.
Stay tuned.
try swapping out the LPG injector itself
so you pressure washed the truck too eh?
try taking some contact cleaner and spraying it in the connectors to remove any 'would be' moisture that may have gotten in there.
If you can get to the ECU circuit board (maybe removing the cover) and spray it also (with the battery disconnected of course)
anywhere that may retain moisture
then blow it out thoroughly
see if that makes any difference
Today, I checked continuity on various circuits relating to LPG fuel injection and the LPG pressure sensor.
I found no open circuits and very dang little resistance in the wiring either.
Thinking possibly the Injector Driver could be faulty, I pulled another Komatsu off of our dock and volunteered it to be guinea pig for an experiment.
I took the Injector Driver from the ailing truck and plugged it into the harness on the "test" truck and tried it out.
Truck ran for over 10 minutes, never missing a beat and no codes were thrown...........MIL stayed dark.
So I put the driver back on the ailing truck and hooked up the Hitachi SST to see what it might have to show after sitting the weekend.
Now the thing is showing 3 codes:
1240= "LPG_F/INJ1 MALFUNCTION (INJECTION)
1241= "LPG_F/INJ MALFUNCTION (NO INJECTION)
1245= "LPG FUEL PRESSURE SENSOR HIGH, INPUT MALFUNCTION"
I am getting all 3 of those DTC with the new ECU and the old ECU, plus with the old ECU I also get 0031.
I am beginning to think possibly the wiring inside the harness is "leaky" and having gotten wet when we washed the truck last week.............there is now some "cross feed" taking place that is scattering the ECU's brains.
I know this is scattering my brain some.
Anybody want to touch this?
Another thing that annoys me about a lot of manuals in general is how they will feature a page of "Abbreviations Found In This Manual" and this list contains about 10 entries (some of which NEVER actually come up in the book).
And then the book is chock full of unexplained abbreviations which defy you to decode them.
For example, I see 5 pins listed on the ECU diagram as AVCC or AVCC2.
No where in the book can I find any decoding of that abbreviation.
I have even tried web searching the term but come up empty headed.
I believe that technical publications are by law compiled by dozens of separate committees that have no communication with each other ( and probably don't even know there are others besides their group) and simply submit the chapter they were assigned to do.
Then the lot is tossed into a barrel and sent to the printer (all except a few pages which are lost along the way, also required by law) :^)
well well this puts a whole new light on the subject
so there has been some backyard engineers working on this prior to your honor of working on this?
I feel for ya man *sighs*
On the Tier version i was going by what the site said about this model number truck, i guess its outdated just a tad. But yeah it is more than likely a Tier II then.
On the code listing this does not suprise me much, sometimes they have a bad habit of putting information in one part of the manual and leaving it out of another where it should actually be. I suppose if i had read through the whole thing instead of trying to find the exact information in a particular place in it i would have seen this. Skimming i guess is no good in this case :o)
All i can say is good luck finding this because it sounds like you'll need it. I'm sure you will find it though.
Edwardt,
yeah i went back and reread that and yep :o)
Second portion of response.
Jplayer, I felt like I was going to exceed some word limit or make it too long for members to be interested, but I gave it a try. Thanks for staying with it.
Truck is a probably a 2005 build as it has the OPSS (KOPS) seat interlock, but it only controls the transmission. My understanding is that the B-56 rules to include mast hydraulics went into effect with 2006 year model.
At any rate it is an EPA Tier II truck.
The O2 sensor appeared to be recently replaced due to the overall "new look" of everything about it.
DTC 1241 is cited in our Komatsu SM 300 service manual in Appendix 3, ERROR CODE LIST on page A3-3. DTC 1241 is not listed in the manual section called "Self-Diagnosis and Malfunction Detection Condition" beginning page 5-50 of SM 300. If you have the appendices listed, that is where I found the DTC explained.
I tried resetting the ECU (erase codes) but DTC 1241 returns immediately when engine is started using the new ECU.
If I use the original ECU, DTC 0031 AND 1241 return immediately when engine is started.
Using the SST I can confirm that the codes WILL erase but will be present again when the engine starts again.
I'm not sure but I feel that the relay box and other items are likely chosen by Nissan for use with their K-engines, regardless of whose truck it is in.......even though the actual harness work will probably vary a lot dependent on truck OEM.
I know that the injector driver is made by Nikki.
Thanks to both of you for posting. I will update the thread as I find an answer.
One more thing. I mentioned that this truck had been "worked over" by butchers or RSB artists. The O2 sensor connector on the chassis harness was broken (probably cause they did not know how to unplug it) AND the locking lever on the Injector Driver connector was missing (probably for the same reason.
I salvaged all the harness connectors (just the ones that had not melted) from the other truck in May, so I have used those parts to restore the items on this truck
edward t, thanks for the info regarding potential "harness R&R".
If my continuity tests show an open circuit in the harness I will likely petition my boss to let us go that route if Komatsu is receptive to letting us have the harness "at cost".
As to "tampering" with wiring: When we received this truck, it was evident (to me) that it had been in the hands of a "butcher"
(or as one of my colleagues calls them "rip, schitt, bang" artists) because the dash harness was not secured in place by any of the OEM bend tabs and all of the OPSS (KOPS) relays were hanging down like a cluster of grapes on top of the left tilt cylinder. The dashboard panels were missing most of their mounting bolts and the small filler panel under the monitor was not even found. Also about 80 % of the plastic wire loom anchors have been cut with snips and no attempt at re-securing anything can be seen.
And..........the large and small harness connectors at the ECU have snap-in covers concealing the back side of the connector body (where the wire terminal pins are inserted). These OEM covers are supposed to be secured to each harness end with plastic zip ties..............neither of those covers on this truck are attached to the harness.......and about 1/4 of the small cover has been broken off.
I get the feeling I am actually chasing an "old problem" instead of a new one.
I will do continuity testing and if I find an open circuit I will proceed to contact Komatsu before trying to ID the cause of the open. If Komatsu is not agreeable about a new harness at cost..........I will then try to determine the reason for the circuit being open. In order to physically check the integrity of each wire where it enters the back side of the harness connector I would need to unwrap a few inches of tape in order to have enough "slack" to tug on the individual wires to check for breakage.
I do smear some dielectric compound on the connectors prior to mating them.
As an aside remark: I had to replace both the dash harness and the main chassis harness on another copy of this same truck back in May of '12. That was another case wherein the truck was sent to us from another location for us to fix.
It was a catastrophic scenario caused by somebody, somewhere, sometime in the past had decided to create an unauthorized (and ill advised) new circuit for some unknown reason by inserting the twisted bare end of a run of 10 gauge wire (THHN no less) into the back of the fuse box of the "battery hot" buss. This wire was routed along side the chassis harness coming down past the left tilt cylinder and simply laid loose along side the left cab frame member.
This wire had apparently gotten between the metal floorboard panel and the cab frame and shorted out.
I'm pretty sure that shorting event vaporized the OEM fusible link in the cab feed tap at the starter solenoid lug because the OEM Komatsu fusible link had been replaced with.........a hand made eyelet terminal and spade terminal and 3 " of 12 gauge wire.
So if my suspicions are right about that, the idiots may have been given 1 chance to "do right" and get rid of the shorting wiring, but instead they chose to eliminate a safety item (fuse link) and the stage was set in grand fashion for the next shorting event with the improper "hot wire" jammed into the fuse box buss. And SHORT it did!
With the fusible link out of the circuit......the wiring inside the dash and chassis harnesses began sagging and at some point a small ground wire got into contact with the big cab feed battery hot conductor. That must have been a flash point because I opened up the entire length of the dash harness and most of the chassis harness and it was all a very melted mess. The 2 harnesses cost us over $1,800 in parts alone. (I just tried to submit my response and was informed it was too long. So I am breaking it into 2 posts. It may end up with a "discontinuous" flavor.)
John, that was one of the nicest things you have ever said to anyone here, ["I think i just had an anuresim reading all that"]....
what is an "anuresim",
and was it good for you too?
lol just joking, now, meanwhile, back at the shop...
based upon the description of where the fuel pressure sensor is on this unit, I would say it is 2005 or newer*
*="ECU I had ordered was configured for the early version K-21 which has the LPG pressure sensor mounted atop the injector body with two 5mm screws. But the ailing K-21 I'm working with has the later version of LPG pressure sensor which threads directly into the front of the injector body".
i think i just had an anuresim reading all that... lol
just kidding :o)
you do seem to have an odd problem here but maybe it isnt so odd.
After reviewing the service information on this truck from what i can get it is a Tier1 system?
It seems Tier 1 had alot of issues with these kind of things
- wire breakage
- bad relays (or relay box)
- bad grounding (at the frame ground point)
- connectors (corrosion, terminals,wire breakage)
these are just a few of the main examples we experienced with the cat trucks using this same system.
Komatsu does show a relay box that contains the same relays as the cat system does. I'm just wondering if its the same relay box. I would start there.
I did read through the EC part of the manual and there are several systems that can trigger the 'failsafe' mode and whatever is happening here is triggering the 'failsafe' and shutting off the LP solenoid as a safety precaution. I found it odd that the EGO circuit (code 0031) can also trigger this action according to the chart in the manual.
This code 1241 eludes me though as it is not listed in their code list. Not sure what it pertains to UNLESS when you installed the other ECU it was for a completely different model and this code was included in THAT particular model. I find that unlikely though because generally All Tier 1 systems utilize the same structure in codes. Maybe it is one of those 'unlisted' codes only the factory or component mfg knows about? Hard to say.
Maybe this 1241 was something that got stored in memory and is lingering until you do a diagnostic reset? i assume you already performed this proceedure? The code is still persistant?
Might want to try unhooking the battery for an hour or so or even overnight to clear all memory. Then start up the truck and see what pops up then? If it starts bringing up random codes again i would look back at the relay box, mainly the EGI relays or even the box itself. We had several box's go bad internally due to the metal bars inside it breaking due to incorrect assembly, they were under a strain and cracked and broke internally because of this. The ultimate result was codes popping up and engine not wanting to start.
Oh yeah, if you do have the SST tool for this truck try testing the EGO sensor with it instead of ohming it out. Even if it does pass and there is a question if its really good or not i'd replace it anyway. Have seen issues with pigtails on some of these sensors.
Just a few things that came to mind while reading your post while eating a sammich and drinking a cool glass of tea ;o)
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