The hydraulic temp guage doesn't work. I bought this dozer last fall and the guage never did work for me. I've found a wire going to the bottom of the hydraulic tank to what could be a sensor. Is there any way to test this sensor? I doubt wether it is just the guage. What else could it be? Thanks
If it is a temp sensor for the gauge it will be a single wire. If you ground that wire to the frame with the key on the temp gauge should go to hot. That will tell you it's the sender , not the gauge or wiring that is the problem. What is the serial number?
The serial# starts with 3CR. That test sounds easy enough. Can't wait to try it. Thanks
If you have some electrical diagnostic capability (in other words a digital multimeter and the knowledge how to use it) I can e-mail you the complete electrical schematic. If you would like the schematic please send me a PM with your complete machine Serial Number and your e-mail address. Question: When you turn the key on and the instruments all do their self-test does the hydraulic temp gauge sweep from zero to full and back again ..? Also, if you look in the top corner of the Alert Indicator (the box below all the warning lights that has the hour meter reading in it) can you see the words "SERV CODE" lit up after the self-test is completed, or do they illuminate then go out when the test is complete..? If SERV CODE stays lit you have an active Diagnostic Code, probably related to your hyd temp gauge.
When the key is turned on the hyd. temp guage goes up half way, then down, then all the way over and then down. The following numbers on the screen are 030 96.03 0.30 819.02 113 168.03 113 168.04 113 692.07 END Nige, I'll pm you the serial# as it would be good to have the schematics.Thanks Also I see a single wire going to the bottom of the hyd tank
Basically the self-test proves the gauge in the cab is working. Your Fault Codes are 030-096-03 - Monitor System, Fuel Level Sensor, Voltage above Normal. 030-819-02 - Monitor System, Display Data Link, Erratic, Intermittent or Incorrect. 113-168-03 - Transmission Control, Electrical System Voltage, Voltage above normal. 113-168-04 - Transmission Control, Electrical System Voltage, Voltage below Normal. 113-692-07 - Transmission Control, Transmission Solenoid #2, Not Responding properly. I don't see anything for your hydraulic temp sensor which surprises me a bit. Now, when you turn the key on for the first time and it scrolls through the codes above, look to see if the "SERV CODE" light is illuminated as each one scrolls in the display. If the SERV CODE is lit, the Diagnostic Code in question is Active and needs to be diagnosed and fixed, if the SERV CODE does not light the Diagnostic Code was there at one time but is not there now (logged Code). We'll get into clearing codes a bit later.
There is no serv code when any of the numbers are displayed. Good thing! The dozer operates perfectly so must be old logged codes.
I think the reason there is no Diagnostic Code for the hydraulic temperature is because it is a simple temp. sender, not a sensor. You have mail.
I recieved your mail. Hope I can sort this out. Thanks Nige!
I removed the 4 screws to pull the monitor out but it will only come part way so as to protect itself from someone like me. I looked at taking the cowling off that surrounds the dash but it's not coming either. Any ideas to the proper way to remove what's necessary to get to the wiring?
Have you tried grounding the wire at the sensor yet?
I haven't tried that yet but will do. It will be easier than trying to find the other end of the wire. Yesterday was a busy day changing transmission oil.
I grounded the wire and the guage didn't move.
remove the sender wire again, and check voltage between that wire to ground, key on. Should be 5V or 8V. Has to be a digital multimeter, not a test light. If no voltage on that wire, there is a continuity issue between the end of the wire and the monitor module, possibly right at the module, but could be anywhere in between.
That circuit doesn't work like that, or so it appears to me. The temperature sender in the hydraulic system has an internal resistance that varies with temperature. This resistance will be typically about 3000 ohms @ 25DegC and about 70 ohms at 110DegC. The sender produces a resistive signal which corresponds to the temperature of the fluid and is then used by the quad gauge module on the cab to interpret to a temperature reading. Looking at the electrical schematic there is only one major connector (CONN 19) located between the sender and the gauge cluster in the cab. It appears to be located right behind the dash panel. Would it be possible to measure continuity in the Grey #442 wire between the sender and CONN 19, then measure continuity in the same wire between CONN 19 and the connector on the back of the monitor unit...?
yes, exactly, it is a NTC sender... as the resistance drops, the pull up voltage or "feeler" out of the control gets pulled closer to ground (0V). That why when you ground it, it registers high temp. because you pulled the voltage right to zero. Therefore with the wire off, you'll read full pull up as long as the wire is continuous right back to the pin on the control. Same concept as the old switch inputs to the old EMS system. This is just variable where EMS was all switches pulling the V to 0, or leaving it at 8V. I just forget what the pull up V is on the newer system. 5V or 8V I forget which for Cat Monitoring systems now, it has been 5, 8 and 12, and VIMS used something weird like 11.7V)
Gotcha. You're right, disconnected from the sender the voltage between the wire and ground should be "stabilized voltage" from within the Monitor Module. All I can see looking at the schematic is an "+V sensor" stabilized supply for the PWM sensors, I assume the same voltage would be applied to the senders, it's not logical for the control to generate a different voltage (although I can vaguely recall some ECMs that had both 5V & 8V stabilized supply because they were running different sensors). However I would I agree with you, usually stabilized sensor supply voltage on a non-VIMS machine is either 5V or 8V, I wouldn't expect both.
I tried a digital meter and it shows that power is coming but like Nige said you have to know how to use it. I'm not sure what setting to put it on and tried to attach a pic of the meter but unsuccessful so will try tomorrow night.
With the wire disconnected from the sender what voltage do you have between the end of the wire and ground with the machine powered up (i.e. key switch in the on position but the engine off)..? Does the reading on your digital meter remain steady within reason..? It may vary just a little, maybe +/- 0.1 volts maximum, but should be basically a steady reading. If you have a steady voltage at the end of the wire IMHO all indications point to the hyd temp sender unit being bad.
Today was the warmest day since I bought this dozer(20C) and this is the first time I've seen the temp guage working. It appeared to work fine in the normal range. I hope it's problem solved. Nige the meter was erratic with the key on and engine not running.