I have a cat 938F that we have been having issues with the quad gauge monitor that shows , fuel , engine temp, trans temp and hydro temp . When you cycle the key the gauges will sweep as like they are supposed to however 80-90% of the time none of the gauges will read . Every once in a while running the machine the gauges will come alive , read correctly then go out. Recently the gauges began working ( they worked for 3 or 4 days which is the most we’ve ever had them work. Got in machine today and once again they are not working . We did order the quad gauge monitor and that did not change the issue . Any help is appreciated
An expensive Parts Cannon for no result......... You need the electrical schematic for a start. Post a Serial Number please.
Attached is serial#. Yes we originally believed there was an internal issue with gauge . Clearly that was not the case …
I'll send you an electrical schematic. Keep an eye on your message inbox. A couple of questions for a start: - 1. Do all the gauges in the quad gauge assembly sweep full scale every time when you turn the key to ON.? The "every time" part is important. 2. Does the tachometer/speedometer display behave the same as the quad gauge assembly when you tuen the key ON.? 3. Does the speedo/tach module display correctly when the machine is operating.? In other words does it show ground speed, engine RPM, and the selected transmission gear.?
Here's another question. On the display window of the Monitor System Panel (RH dise of dash) an icon SERV CODE should appear when you first turn the key ON. At the end of the panel self-test does that icon disappear or stay on.?
Sorry for delayed response . Gauges only do 1/2 sweep. To my knowledge they used to full sweep . It appears now it is only half sweep. This machine does not have a tac/ speedometer , it just has the gauge set with hour meter , and warning light set above . I tried to upload a video of the gauges but I for some reason can’t upload . Will attempt To upload .
I believe the icon disappears , but I will Double check tomorrow. Thank you for Any assistance you can give NIGE
You can only upload photos. To upload a video you have to host it somewhere else first then link it in a post on here. Whether the SERV CODE icon disappears or not after the boot-up sequence will be key to how the diagnosis moves forward.
I’m sorry for being rude - but what was the logic behind replacing the gauges, if they been sweeping OK all this time?! I apologize again!
We replaced it because because we thought it was an internal issue inside the gauge cluster …. Nige will confirm this tomorrow . Thank you
See there's the thing. If the gauges sweep when the key is turned on, even if it's not full scale, there isn't likely to be much wrong with the gauge module.
Sounds more like intermittent loss of ground to the module.
We'll have to see........ I hope it is, but my gut feel is that there is a problem further upstream in the monitor system.
So Serv icon stays illuminated and lists the following codes
Attached is additional codes
CID 248 FMI 2 might be it. Communication issues? Data received not expected.
Also Coolant sensor, ECM low voltage detected and particular trap inlet pressure sensor, downshift solenoid.
See if you can find twisted pair of wires going to that module, check the connection, put the ohmmeter across them and measure resistance should be 60 ohm. If it is 120 ohm - you have problems with terminating resistor. Don’t shove multimeter probes in to female sockets if the connector - just touch them.
Ok will try this this tomorrow or Saturday , thank you for the info , is the terminating resistor something that can be changed ?
Yes. And they do go out, or get bad connection. It should look like a two wire connector that plugs in to wiring harness. Nige should help you with locations. But then again - usually they create more mayhem than one component malfunctioning. But they make network do weird stuff.
No terminating resistors on this machine. It's far too old. It uses Cat's proprietary Datalink not the latest generation of CAN Datalink. I see a lot of photos but not one of them with the SERV CODE icon lit indicating that the Code on the screen is Active. Can you possibly try again please, starting with a photo of the Monitor Panel taken with the engine idling showing the SERV CODE icon lit up. Having the engine running will remove the likelihood of any spurious low voltage Codes that may be present when the engine is stopped. The image below shows an Active Code. Each Code will appear in two consecutive screens as follows MID (030, 081), CID (110, 248, 621) and FMI (02, 08).
Thanks Nige will update tomorrow .
Dang Nige! Im feeling young all of the sudden! Talking 1939 here!
Just trying to prevent you diving down the wrong rabbit hole........
My bad! Sorry!!!
Nige Apologize for delay… I show one active code with service icon illuminated . Let machine run for approx 5 min to eliminate any possible low voltage codes .
Look up thread here called “cat monitoring system”
Thanks TVA , will do
OK, so now we are getting somewhere. You have 819 F02 which relates to the transfer of information to/from the principal Monitor Module and the Quad Gauge Module and the Speedo/tacho (if equipped) module. See the attached troubleshooting procedure. Also check your message inbox for an electrical schematic. You're going to be digging into the dash panel........
I bet on quad gauges connector
Or contamination in the (unused) connector on the branch of the harness to the speedo/tacho module. Or maybe even crusties in the Main Monitor module harness connector.
You are correct.Everything needs to be checked out, diligently.
Nige, we have gone through testing procedure. I’m going to have a friend who’s a mechanic go over test with us Again and see if we have any different results , as of now we did entire procedure , have found no broken wires , no corrosion. No chafes , nothing indicating that we have a wiring issue. I’m not brain dead , but I also wouldn’t consider myself a master mechanic and would like a second set of eyes to Go through procedure . Have you ever seen the message center module fail? We made It to step 5 and have 9 volts to message center module.
Is anything “aftermarket” installed close to the cluster. Some kind of high power or high frequency device? That can produce EMI, or any kind of wires goes through it?
Nothing aftermarket , no speedometer or tac in this machine, nothing inside this machine has been messed with. We are third owner bought from a friend. We did add a radio with factory harness. No difference with radio Installed or prior to .
Can I ask if you can spot a Part Number marked on the Message Centre module.? Did the procedure direct you to the conclusion that the Message Centre module is bad.?
Radio is just a receiver - it wouldn’t emit EMI Maybe I’m fantasizing here, it’s my Industrial Control and Communications experience kicked in.
Step 5 is a bit confusing, even to me and I know my way around it well. Note the title of the Step - "CHECK FOR + 12 DCV." You are looking for the presence of +12v DC, or battery voltage if you prefer.. That is what the module is supposed to be outputting if everything works as it should. If you see 9.0 ± 0.5 DCV then the Monitor Module has failed. Back to my question of what Part Number is marked on the module in your particular loader.
Try a couple of simple tests. 1. Unplug the Quad Gauge module from the machine harness. Turn the key ON and measure the voltage again by pack-probing between Pins 1 & 2 of the Main Monitor Module connector. 2. Quad Gauge remains unplugged. In the dash panel remove the lamps #2 & #3 from the Ride Control Indication and the Auto Ride Control. Key ON and again measure voltage between Pins 1 & 2. For both of the above tests are you still measuring 9.0v.?
After sleeping on it I have a better and more definitive test for you. Unplug the 40-pin connector on the back side of the Monitor module. Key ON, what is the measured voltage between Pins 1 & 2 of the connector.?
Did you ever get a resolution to this.?