1. I need a service manual 2. how do you raise the water level of the machine

The water level sensor is a pressure switch and there is setting to which as the water gathers into the TUB the pressure exerted on the diaprgram within the pressure switch will correspond and determine the point of switching. So to increase the level within ( make sure that the switch is working as a damaged pressure switch will REQUIRE more water pressure to switch -- faulty diaphragm.)
To increase the level you can set the diaphragm controller to a higer setting-- this provision is seen on most pressure switches so that a higher pressure is needed to switch on thereby the water level goes higher.

Http://www.manualowl.com/p/LG/WM3885HCCA/Manual/77746
Hi i searched extensively for a service manual for this exact model, however have been unable to find one? Above is a user manual, perhaps this may help? In any event also below is the LG Link, perhaps if you contact them they will be able to provide you with either a manual, or indeed a direct answer to your question.
http://www.lg.com/us/support/index.jsp

Hello cont... go to this link and click on learn more...

http://www.searspartsdirect.com/partsdirect/part-model/LG-Parts/Washer-Parts/Model-WM3885HCCA/3204/0153200?pathTaken=&prst=0&shdMod=WM3885HCCA

Joe

Hi.

You cannot adjust the water level we design washing machines to work with a volume of water that is determined by the water level. Increasing the water level over design specifications will result in leaks, and in time will cause structural damage to drum bearing at the back of the tub and strut supports in front. I am not guessing to earn a couple of dollars. I am an engineer expert in appliance design.

In short: the water level of modern washing machines is not something that you can adjust. The water volume is determined by the water level switch at fixed values. If the water level switch is defective, replace the switch

In your case the machine does not use a simple pressure switch. The pressure is detected elaborating the output of the vibration sensor and pressure switch. This results in a ten steps water level response. The sensor output is used on the principle that different volumes of water result in machine vibrating at different frequencies. The pressure switch works along the vibration sensor. Its role is only to detect if water is empty or if it reached overfill level. This is only a two levels device with three contacts. There is no way to adjust or program either one.

If the machine is underfilling you need to check hot water inlet, vibration sensor and pressure switch, and then replace or repair the defective part. You test the vibration sensor reading its response frequencies. This is done using machine own diagnostics, as explained at page 22-23 and 36 in service manual below. The pressure switch is tested reading impedance at its contacts or using machine diagnostics. If there is low filling check also the pressure of the hot inlet hose. Hot water is filled after cold water. Low hot pressure may result in low water level. This particular machine is supposed to detect the condition and report the problem, but in some case that may not happen because the vibration sensor is not functioning correctly.

There is no answer to one of your two questions. On this machine the water level switch and the pressure sensor are not programmable or adjustable. If either one is defective, simply replace the part. Both parts are located in control assembly. Both can be tested using machine's diagnostics and a multimeter, as shown in service manual.

Please let me know if you need further explanations or if anything in my answer is not clear.

Here the service manual. Please click to open the manual in PDF format.

Best regards.

Ginko