Caterpillar 735 articulated truck will not shift out of first gear on flat or uphill grade but will downhill. It's really got me puzzled! Any suggestions would greatly be appreciated.Reverse works normal.
What rpm are you reaching. Hold gear switch on maybe.
Hold gear is not on or is in 8th.. About 2150 max on rpm
S/N prefix of the truck please ........... B1N perchance..? Is there any significant difference to the maximum engine RPM you see when travelling on level/uphill (when the truck refuses to upshift) compared to downhill (when it will)..? If the engine is getting to higher RPM downhill than it is level/uphill then it would appear there could be a problem with lack of power. If there is no difference, read on. My first thought if there's no difference in engine RPM uphill or downhill would be that for some reason the Lockup clutch in the converter is either not engaging at all or only partially engaging. On a downhill run even the lack up a lockup clutch would in all probability probably not prevent the truck ground speed (assisted of course by gravity) getting to a point at which a transmission upshift would be triggered. Hence the transmission upshifts.
I'm here at it now and it says model 735....product id # CAT0075.. circumstances up to this point were..throwed code for trans filter stop up,changed all oil and filter. It was not going into drive most of the time. Sometimes it would. Fluid had lots of metal on both magnets and fluid was black. Now it goes into gear fine just want shift out of first on level or uphill
Any service codes or lights on? That rpm should be OK. What speed is the dash reading mph?
4 mph and it throwed the code for the filter being stopped and the warning alarm sounded and wouldn't go off. That stopped after I changed filter and oil.
Lots of metal on magnets............. did you maybe take a photo of the metal..? Black fluid - maybe something's burnt, most likely a clutch. Did fluid you drained smell burnt..? Any idea when the oil was last changed and how many hours the truck's run since..? Could still be the converter lockup clutch because the whole powertrain (converter & transmission) shares the same oil. Did you get chance to check engine RPM on level/uphill versus downhill..? Any difference..?
No difference on rpm and when you start out downhill it goes for a little bit before it shifts to second then it goes on through the rest of the gears like it should. Seems like not enough ground speed and the converter issue would make since
No difference in engine RPM and I would be looking at the lockup clutch next, if nothing else than to eliminate it from the fault diagnosis. A slow shift from 1st to 2nd downhill followed by (relatively) "normal" upshifts beyond 2nd could be another pointer towards the LUC. Remember 1st gear is the only one that has both converter drive & lockup, 2nd upwards is direct drive only. When you're driving the truck can you feel the LUC engage..? It should feel a bit like the truck has changed gear but in actual fact it hasn't. Is that the only 735 on the job site..? if there are others then try driving one of them and see how the LUC feels when it engages. On larger trucks it's quite noticeable from the seat, not sure about an Articulated. That looks like "fuzz" from normal wear (although maybe in higher than normal quantity) rather than a major component breakup. A lot depends on how long ago the oil was last changed - at which point one would hope that the magnet was cleaned. But do you know this for sure..? That magnet wouldn't necessarily frighten me too much if I knew a bit more of the previous history of the transmission and maybe also had photos of what the magnetic plug looked like on previous oil changes. Something's wearing in there, that's for sure. How many hours does the truck have on it, or the transmission if it doesn't have the same hours as the truck..?
Whole truck has 9660hrs and we bought it at auction. Is there a way to check the lock up clutch or does the tranny have to be pulled. We bought 2 and they came from the same company and the other one was not bad at all and fluid was clearing.
As per my post above (eidted while you were typing probably) ........... try driving the other truck and see if you can feel the LUC engage, then try the problem truck. LUC pressure should be able to be checked from outside. Let me have a look ........... Edit: Need the Serial Number. Look at the last 8 digits of the 17-digit PIN number. They will be something like B1Nxxxxx where the x's are numbers from 0 thru 9.
I had a problem with a 740 playing up with gears and it turned out to be the (actual gear sensor) on the right hand side of the transmission another 740 we had also played up and it was the toothed wheel that the transmission sensor picks up off had come out of place giving false readings
This brings to mind another thought. If that amount of material was on themagnet, what's the chance of some metal particles adhering to the end of the magnetic pickup for the speed sensor..?
AWR00516 is the last 8#s... I know for a fact that the lock up is working on the other one b/c of what you said it would almost feels like it shifts but it doesn't. The one that's not shifting doesn't do it at all. Is there any way to check the converter from the outside???
True that might be worth checking as its relitavely easy to get at at the back of the trans
Send me a PM with your e-mail address. I'll send you the Testing & Adjusting Procedure so at least you'll be able to check the converter pressures. The LUC is operated by a solenoid valve on top of the transmission - one of 3 (upshift, downshift, & LUC). Maybe you have a wiring fault that is not allowing a signal to get to the solenoid valve, or maybe the solenoid valve itself is dodgy. I'll send you the electrical schematic as well so you can troubleshoot that side as well.
[email protected]
You have mail ............
Well I went directly to the lock up solenoid and valve to check the ohm's. It measured a lil high but still in range. So Itook off the whole solenoid to check ooperation of the valve and at first it was somewhat stuck in place, after it came free I checked the ohm's and it read way out..like 4.00 high. It said 8.7+/- .40..it reads 12.5 now. I figured what the heck and hooked it to 12v and nothing,hooked it to 24v and nothing. I ordered a new solenoid from Thompson cat and it will be there in the morning. Hope that fixes my problem and thank you so much for your help!
Did this fix the problem? Hey, Wondering if the new solenoid fixed the problem ?
Hate to Bring up an old thread I just bought a cat 725 2006 model. Driving it to job site went about a half mile transmission filter light came on. Went back to yard and changed it. It shifted fine a little hesitant but shifted. I now have reverse intermittently but it locks in strong and only have first gear on forward shifts to second on display but nothing is there?? I have re-calibrated the clutches. It is displaying codes of Turbo pressure sensor Throttle positioning sensor Fuel level sensor Transmission temp sensor Code that first shows up on start up is 273-0138 which I cannot find out what it means any ideas?
Post a Serial Number for better information. I can check & post the diagnostic procedures for the 4 codes you mention above when I get into the office tomorrow.
B1L699 the last code 273-0138 is the one I am having trouble with. Thank you
T273-0138 is actually the Part Number of the electronic indicator panel in the dash. When you first turn the key on and it boots up it is programmed to display the Part Number during the bootup sequence. BTW there is an updated panel available, Part Number 287-3247. Regarding the other four codes, please can you post details of what is displayed. e.g. something like 091-08 or similar. It will help to identify the correct troubleshooting procedure. Also have you confirmed that those four codes are Active, and not simply Logged meaning that they were there at one time but are not there now..? Turbo pressure sensor Throttle positioning sensor Fuel level sensor Transmission temp sensor
Yes they are active nothing else comes up on dash I am using cat et. I will be getting in those sensors later today because of my location I ordered them and will test and replace them as I go return what I don’t need. I am just wondering if the throttle positioning code can kick it into a limp mode only leaving first gear? I will update Thanks again
Rather than replace sensors wholesale to "fault find by substitution" would you not be better advised to go through the Troubleshooting Procedure for each of the Active Diagnostic Codes that you have..? Some if not all of the issues could be down to a bad wiring harness or connector. Swapping sensors ain't gonna fix that........ If you post the Diagnostic Codes in CIDxxx FMIyyy form I'm pretty sure that I can round up the correct Troubleshooting procedure for each one of them.
Active codes Engine side 1589-3 turbo inlet pressure voltage above normal 91-8 threottle position sensor abnormal frequency, pulse width, or period 96-3 fuel level sensor voltage above normal
Performed throttle position test O% at idle 100% at wide open throttle
There's your problem (I think). The throttle sensor signal needs to be between 7% (Idle) and 95% (WOT). Procedures attached. A suggestion. Pay particular attention to every electrical connector you open, especially the big ones. Get in there with contact cleaner big style. The turbo inlet pressure sensor shows as CID 275, but the procedure should be the same although you might have to pay attention to wire numbers in the harness. That sensor is part of the signals that measure air filter restriction (and control engine derate). Maybe that's where your issue lies..?
Hi, everybody! I have very old dumper cat 769 and there is a problem - works only 1st and reverse gear. Mechanics says it's electric trouble, but wires, selector and gear module works correct dye to diagnostic panel. Solenoids are clicking when current on.
There is such diagnostic dashboard, who knows, is a colour of leds has the meaning?
First thing. Start with a Serial Number please. That photo looks like an EPTC-II. Does the truck have an electronic transmission output speed sensor.? It will be located on the front of the transmission right at the bottom, probably behind a metal guard. But you will recognize it because a wire harness will appear from behind the guard.
This is serial number. I'll check speed sensor tomorrow. Thank you!
So you have a 769C. That will have an electronic speed sensor fitted. Did the problem of not shifting past 1st speed forward develop suddenly or has it been happening on & off for a while.? If it was sudden I would suspect that either the sensor has failed or possibly a cut wire in the harness to it. If there is a cut wire it ought to be easy to spot. If it has been happening intermittently for a while I would be looking for a bad connector (corrosion.?) somewhere between the sensor and the electronic control in the cab. I need to look up in the system what the LED lights on the control indicate.
There is a red led of sensor at diagnostic panel. But i don't know what sensor. It's glowing all the time
Hopefully I’ll get a few minutes to jump on the system and check out the LED meanings later. I know I said before that at first glance it looked like an EPTC-II, but thinking about it I’m not sure that the smaller trucks like the 769 didn’t have a slightly different transmission control module, because your photo looks somewhat different from the modules I remember on the big trucks.
OK, so what you have is a 1st Generation Electronic Programmable Transmisison Control (EPTC) as opposed to the 2nd Generation EPTC-II. Do you have an Electrical Schematic for the truck.? - Because you are going to need one to do a number of the tests. Basically your LED lights are as follows, starting from the left of your photo. 5 lights showing the transmission control lever position - in other words which transmission clutches the lever is commanding to be engaged. 5 lights showing the signal from the Actual gear switch mounted on the rear RH side of the transmission - in other words which transmission clutches are ACTUALLY engaged. 1 light for the transmission speed sensor pickup signal. 1 light for the retarder system active. 3 lights. One for each of the upshift, downshift, and torque converter lockup solenoids.
Have you tried shifting the transmisison manually using a pair of vice grips on the shaft on the end of the actual gear switch on the side of the transmission.? To do that you ideally need get the rear of the truck up on stands and remove the tyres - it can get more than a bit interesting sitting on top of the transmission with the dump body raised and the rear wheels spinning at high speed right next to you....!! If you do this you need to pay particular attention to ensure that the front wheels are securely blocked against unwanted movement and that there is no possibility that the truck can slip off the stands holding up the rear end.
I think, Electrical Schematic i have is not actual, because i found some inconsistencies between diagram and connections. I noticed, when dumper was in motion, that leds of actual gear switch were like 4 gear is opereting, but real is 1 gear... It means leds are changing, but gear is not. Does colour of leds mean anything or not? Thank you very much for assistance
I sent you a message.
I also have a 2007 725 with the same shifting problem has first and reverse shows shifting into second but doesn't shift
I found, that when truck moving, control unit didn't watch it, lamp of the speed sensor is always on. We checked speed sensor, wire, they were ok, but we don't have a new transmission control unit( we didn't have solution(
Does the lockup clutch engage.? You should be able to feel it engage if nothing else. If you didn't know better you'd think it was shifting a gear.
Could you resend please i did not get it
B1L01450
We ran the transmission fill calibration and at the end it says calibration unsuccessful -Error Code : 1023 Transmission Clutch 1 at a limit -Error Code : 1024 Transmission Clutch 2 at a limit -Error Code : 1025 Transmission Clutch 3 at a limit -Error Code : 1026 Transmission Clutch 4 at a limit
If you tried to calibrate the transmission clutch fill you obviously have (or have access to) Cat ET. What Diagnostic Codes are logged/active in the machine at the present time.? BTW the message referred to in post #41 was not for you, it was for the poster from post #40 on the previous page.
Right now only active code is 96-3 fuel level sensor above normal
Ok, dead end there then. Pressure test the transmission/converter/retarder system would be the next step I think. Procedure attached just in case you don't have it.
Hello Everybody. We have a CAT 725 dumper with serial AFX01521 and it won't shift to the 4th gear. It's trying but doesn't get it in the 4th gear so it will go back to the 3rd. Has anyone an idea where to look?
I know it might be difficult in Holland but does it upshift to 4th speed travelling downhill.? Does the oil smell burned.? Have you cut the transmission filter to check for the presence of particles.? This is an important check because you may have failed the #2 clutch in the transmission. Have you tried the powertrain pressure tests per the attachment in post #50 above.? EDIT: You also should get hold of (or make) a Click Box so that you can put the electronics into Service Mode and check what Diagnostic codes might be present. It's unfortunate that your machine does not have the Scroll/Clear switches on the dashboard that are referred in Post #37 on Page 2. See this thread..........
Here is the clutch chart for your transmission. as you can see the #2 clutch is never used until the transmission goes above 3rd speed. IMO the finger of suspicion points at the #2 clutch. It could be a failed ECPC modulating valve for that clutch or the clutch itself has failed. Getting the Diagnostic Codes is the critical thing right now - if there is a code for the #2 clutch solenoid valve then you know straight away where to look.
Thank Nige, i don't have time now to check but i will come back later. I will check the oil and see if the ecpc valve is working correctly. No hills at all here but the machine has enough power so don't think that's the problem.
Yeah, I wrote it a bit tongue-in-cheeck just on the off-chance. Personally I would check the oil colour, clarity (it should be bright & clear, not cloudy), & smell first, then cut the filter & look for debris. A clutch failure will be obvious from the results of that inspection, the filter will have a lot of black gritty particles in it which is the remains of the clutch disc friction material. If you find nothing then the chances of a burned-up clutch would seem unlikely allowing you to focus on the electrical side.