Cat 312 sensors and display

I have a Cat 312 excavator im working on. Serial number 7DK02298, its a Japanese import model. Have a few issues im wondering if anyone has run into before. The display in the cab shows CAL in the upper right corner, the red LEDS are flashing, and the coolant temp and hydraulic oil temps are pegged all the way hot with the warning lights on as well. The fuel gauge functions properly. I tested both temp sensors and they are open. One wire has 12 volts on it and the other is ground. When I put a 2k resistor across the two wires nothing changes. The throttle cables were melted and the electric throttle wasn't working. Im waiting on a new actuator/cables, which I know ill need to calibrate. Is that why the CAL is flashing? Does that also affect the temp sensors or is that something else. Thanks for any input

Was the display showing CAL before the cables melted.? Do you have an electrical schematic for it.?

BTW in case you were not aware the service information for 7DK02298 is the same as that for a non-Japanese 312 machine in the Serial Number range from 6GK1-6GK392. Generally only the cabs and sheet metal differ between the two models.

Yes, I've read in some other threads about the similarities between the 7DK and 6GK models so that does help. Just have been finding spotty information online so far. Another thing I noticed is if I enter data mode and check codes it has error codes E26 and E28, which aren't listed on the code list I found. Also the engine rpm reading in data mode ranges from 150 to 350. It seems to read consistently in that range, but is 1500 to 3500 the correct operating range? Its been showing CAL as long as we've had it. The throttle did function partially earlier but I had not got around to figuring out how to calibrate it

massey4900 said: Yes, I've read in some other threads about the similarities between the 7DK and 6GK models so that does help. Just have been finding spotty information online so far. Another thing I noticed is if I enter data mode and check codes it has error codes E26 and E28, which aren't listed on the code list I found. Also the engine rpm reading in data mode ranges from 150 to 350. It seems to read consistently in that range, but is 1500 to 3500 the correct operating range? Its been showing CAL as long as we've had it. The throttle did function partially earlier but I had not got around to figuring out how to calibrate it Click to expand... I worked on a Cat 312 about a few months ago that Nige supplied schematics for. The battery cables were horrible and had to redo some Ground cables. There is a flat strap by the fuel injection pump where the intake Heater is situated that I had to replace. Melted Throttle cable points strongly toward a poor ground cable on engine or around. The machine I worked on had a junk Throttle cable also as these machines are quite old. Best check these simple things first. Simon C

In the case of the two temp senders try disconnecting the wire at the sender location. What happens to the gauge reading.? Spec for 4I-5394 Hydraulic Oil Temp sender as follows. All values in ohms: - 20824 to 25451 at 0°C (32°F) 6134 to 7496 at 25°C (77°F) 3989 to 4875 at 35°C (95°F) 2224 to 2718 at 50°C (122°F) 973 to 1189 at 75°C (167°F) 475 to 522 at 100°C (212°F) 221 to 269 at 125°C (257°F) Can't find a specification for the coolant temp sender unfortunately.

Ive disconnected both sensors and it makes no difference to the display, but that makes sense because im reading the sensors as open anyway. I'll get new sensors and go from there. I'll check over the ground wires as well

massey4900 said: Ive disconnected both sensors and it makes no difference to the display, but that makes sense because im reading the sensors as open anyway. Click to expand... Generally if you remove the signal wire from a sender of that type the gauge reading should go to zero. Touching the signal wire to frame ground should then max out the gauge. I think you may have other issues in addition to the senders.

A contact came up with the specs for the engine coolant temperature sender 5I-7578. Again all values in ohms. 20824 - 25451 @ 0°C (32°F) 6134 - 7496 @ 25°C (77°F) 3989 - 4875 @ 35°C (95°F) 2224 - 2718 @ 50°C (122°F) 973 - 1189 @ 75°C (167°F) 475 - 522 @ 100°C (212°F) 221 - 269 @ 125°C (257°F)

Well, I got the new actuator installed. It works correctly with the throttle knob, and with the manual switches. But when I try to calibrate it, it gets to AC1 and then nothing happens. Let it sit there for 5 minutes, its just at an idle, and nothing changes. The service directions seem to say it should advance through the stages automatically?

Did you follow the suggestion made by @Simon C regarding checking for faulty engine block grounds that might have melted the throttle cables.? Do you have the OEM Test & Adjust documentation for the Electronic/Hydraulic system.?