I have a Cat 963 Ser#21Z00572 with an oil pressure warning light and alarm going off I need help with. History: Running the machine moving dirt and oil pressure warning light and alarm go off. I park machine and next day check engine oil pressure sending units. One of the two senders are cracked. Ordered new cat sending units and installed. Ran machine for about 10 hrs with no issues, then oil pressure warning light and alarm go off again. Park machine. Next day, lift cab and remove one sending unit and install mechanical pressure gauge. Run machine for an hour watching mechanical gauge. Cold low idle pressure 75 psi. Hot low idle pressure 35 psi. Hot high idle pressure 70 psi. I believe the oil pressure is fine for a 7500 hrs machine. Ohms tested the new sending units. OL when not running and 850 ohms when at low idle (cold oil) on both sending units. Checked wiring harness plugs between oil pressure sending units and dash, individual terminals are not corroded. I do not have a Cat Service manual. I have not tried to inspect the dash yet. Is it possible the dash panel could be bad? Any help would be appreciated. Thanks Cliff
I think the warning light uses a 2 wire switch with one side to ground and the other to the ems panel. Make sure you have continuity to ground on the one wire . If the light is on it should go out if you ground the signal wire or jumper the 2 terminals. If that works it eliminates the signal wiring and ems panel. I didn’t go check the serial number and schematic yet so this could be wrong for your model.
I sent you an electrical schematic. Check your message inbox. Have you tried plumbing a mechanical gauge into the oil system to check whether or not you actually have low pressure.? I think I would be tempted to do that before condemning the electrical system.
Search for Caterpillar Publication reference SENR2280. Here's an example for sale on eBay . You should always ask the seller "is it complete.?" In other words are all the manual sections that appear on the contents page inside the cover actually physically present inside the binder.? For reference the new price for a paper version of this manual is $655.
Nige: Thank you for the electrical schematic. In the original post, I said, that I installed a mechanical pressure gauge and got the following: Cold oil (15W40) low idle 75 psi Normal operating temperature low idle 35 psi Normal operating temperature high rpm 70 psi These normal operating temperature readings were consistent for 1 hour of operation. Thanks Cliff
Sorry, missed that. Hadn’t had my morning wake up coffee…! Apologies for the quality of the schematic but it’s the best there is available.