Cat Excavator Control Monitor

Thread Starter

t_glover

Joined Mar 16, 2021
29
A family member recently purchased a 1995 Cat 315C Excavator to do work on their hobby farm.
The machine has a monitor that has gauges for fuel level and engine temp and oil pressure as well
as a few other things it monitors. It also controls several other functions on the machine. They bought it
knowing there was a problem with the monitor. The unit does not power up when the key it turned on.
Today I took the monitor off and disassembled and inspected it and could not see what the problem was.
The voltage regulator is outputting 5V.
Any help sorting this out would be greatly appreciated!

1.JPG
2.JPG
3.JPG
4.JPG
5.JPG

The numbers off the ICs are:
IC1: 4K1RJ HD63BO1YOP

IC3: 9427H 74HC04AP

IC4: HD74HC74P

IC5 PA2004C 9441EH004

IC6 3773P 9428 M89GT

IC8 SN75176BP 40A59TJ

Thanks In Advance!!
Terry
 

LowQCab

Joined Nov 6, 2012
1,096
Check the simple things first, like all of the Fuses.

If all of the Fuses Test good, inspect carefully for any damage to the Wiring-Harness,
especially where You can't easily see it.

~26-Years is a respectable Life-Expectancy for a Board of this type.
It's not likely that You can repair this Display-Board, or find a direct-replacement-part,
especially if You can't obtain a complete Wiring-Schematic for the Board.

If You can, get a Wiring Schematic for the Whole Machine and Post it here.

Start thinking about how You can create a nice Mounting-Panel for
installing some Aftermarket-Gauges.

The various Sensors will have to be changed-out for
the Sensors that come with the new Gauges.
This may require various Thread-Type-Adapters, which are readily available.
This may also require a 24-Volt, to 12-Volt, Voltage-Regulator
if the Machine has a 24-Volt Electrical-System.

Here are some very nice Gauges ...............
https://www.maxtow.com/white-green-maxtow-air-pressure-gauge/
.
.
.
 

geekoftheweek

Joined Oct 6, 2013
692
If you decide to go the gauge route check with cat to see if they have anything available. They may have something available that can pick of messages from the engine datalink and it will just be a matter of running four or five wires. I don't know excavators, but do know trucks were set up that way.
 

Thread Starter

t_glover

Joined Mar 16, 2021
29
I tried powering it up with a bench top power supply with no luck.
I thought about installing gauges but the monitor unit also controls
some of the hydraulic functions. The monitor has a 24 volt power supply
and two data wires that connect by RS-485 to an electronic control unit
on the machine.
I have a wiring diagram its a 836 Kb PDF file. I'm not sure how to post it.
 

BobaMosfet

Joined Jul 1, 2009
1,848
@t_glover

Contact your local CAT dealer via email- they are very nice and helpful. I have a CAT E7 Dozer (65+ ton) and found them to be exceedingly helpful for no cost.
 

Tonyr1084

Joined Sep 24, 2015
6,263
The attached file doesn't show the board schematic. However, after zooming in and scanning back and forth I've found your "Monitor" circuit in zone E2. (look at the top and edge to find A through F, and on the side 1 through 12) On CONN 30, 201-BK should be grounded inside the cab. Check your grounds. A bad ground can cause problems.
1628082713810.png

I just put 22501-KS8001 into a Yahoo search and came up with this:
1628083385223.png
22501-KS8001
Can't read that language, but it may lead to more information on the monitor. It shows a monitor very similar to what yours appears to be. Good hunting.
 

Thread Starter

t_glover

Joined Mar 16, 2021
29
I checked the power supply in the machine and its good. I powered the
monitor up with a bench top power supply and it still is dead.
 

Tonyr1084

Joined Sep 24, 2015
6,263
Without a schematic of the circuit board it will be impossible to assist you in repairing it. Being that it's mostly PTH technology (old school leads through the board) it should be easily repairable IF you can find the issue. Note: Finding the bad part is only half the battle. The other half is finding WHY the part went bad. It could just be age and fatigue, it could be something blown because of some other issue. Failure to discover and rectify the issue will likely result in a new blown board or component(s).

It could be a bad LCD driver chip (surface mount technology). Does ANYTHING happen when you power the board?
 

Thread Starter

t_glover

Joined Mar 16, 2021
29
Nothing happens when I power it up. There are LEDs on the button
pad that should illuminate when its powered up even if the LCD driver failed.
I have seen electronic components on trucks and machinery fail from someone
welding on the machine and not taking the necessary precautions.
 
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Tonyr1084

Joined Sep 24, 2015
6,263
Follow the pink line. It should be the plus line going through an unknown (at this time) diode. The light should light up. Not certain about that, but it appears so. Also appears to be some sort of LED. Possibly Bi-Color. Three lines leading to it seem to indicate that's a possibility. TR8 probably controls it lighting up. Without the board in hand it's difficult to follow the traces and identify all the components; but there's an unknown component (pictured in the lower right corner) under the heatsink. If that's a fuse then that could be the whole problem. ((note: I've flipped the picture vertically to match the wiring on the component side of the board))
1628136233855.png
 

Tonyr1084

Joined Sep 24, 2015
6,263
Just found an email from CAT:

Hi Tony,

Thank you for contacting the Caterpillar Customer Care Team.

We have received your inquiry about part number 7Y-5500: CONTROL GP. We have identified that this is discontinued and has been replaced by part number 490-1015: CONT GP.

To place an order for this part, please get in touch with your local CAT dealer. You may provide us your zip code to locate the nearest one in your area. You may also use our dealer locator tool by using this link: https://www.cat.com/en_US/support/dealer-locator.html.
 
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Thread Starter

t_glover

Joined Mar 16, 2021
29
I contacted the Cat dealer and asked about getting a
rebuilt monitor. They told me a rebuilt monitor
is normally available but they don't have one in
their system right now. I was told if I order a rebuilt
monitor now they would send a new unit for the
same price as the rebuilt unit.
The owner said go ahead and order it.
Thanks Everyone your help.
Terry
 
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