Question 1

weird high pitched whining noise from my bosch drill when i pull the trigger, even without load.

Accepted Answer

DIAGNOSIS The noise is from the motor's armature spinning. The most likely cause is dried-out or failing motor bearings, or lack of lubrication on the armature shaft. FIX Remove the battery. Check the motor fan at the rear of the tool for obstruction. Spin it by hand. If it grinds or is noisy, the rear bearing is shot. The motor assembly must be replaced as a unit. IF THAT DIDN'T WORK The planetary gear set in the front gear housing could be dry. A high-pitched whine under load can be metal-on-metal gears. This requires disassembly and specific grease (Bosch lubricant 2 607 001 005). HEADS UP Do not spray lubricant like WD-40 into the motor vents. It attracts dust and will destroy the motor brushes and commutator. Use only designated electric motor grease.

Question 2

battery doesn't seem to charge all the way, fuel gauge shows one bar then charger light goes green fast.

Accepted Answer

DIAGNOSIS The battery's internal management system is misreading cell voltage due to an unbalanced cell group. It thinks it's full when it's not. FIX Fully drain the battery. Use the tool until it completely stops. Then place it on the charger for a full 60-minute charge cycle without interruption. This can recalibrate the cells. IF THAT DIDN'T WORK One or more of the 3-cell groups in the pack has significantly lower capacity. The pack is worn out and needs replacement. Lithium-ion batteries have a finite lifespan. HEADS UP Do not leave a depleted battery on the shelf. Store lithium-ion batteries at a 40-60% charge state. Long-term storage fully drained ruins them.

Question 3

my drill driver works but the led worklight doesn't come on anymore.

Accepted Answer

DIAGNOSIS The LED bulb is burned out or the wire connecting it to the board is disconnected. The LED is powered independently of the motor. FIX The LED is part of a light pipe assembly. Part number is 2 607 001 038. To replace, you must open the gear housing. The LED is a surface-mount component on a small board in the nose of the tool. IF THAT DIDN'T WORK Check for physical damage to the clear plastic light guide/lens. If cracked, it may block the light even with a working LED. The same part includes the lens. HEADS UP The light is designed to turn on with slight trigger pull. It does not have an independent switch. If it's dead, the tool is still safe to use.

Question 4

the forward/reverse slider switch is stuck and won't move on my ps31.

Accepted Answer

DIAGNOSIS Debris like concrete dust or dried mud has jammed the slide switch mechanism internally. FIX Remove the battery. Flood the switch area with electrical contact cleaner. Let it soak for a minute. Work the switch back and forth vigorously while wet. Repeat until it moves freely. Allow to fully dry before use. IF THAT DIDN'T WORK The switch detent spring or the switch itself (part 2 607 001 039) is broken. This requires disassembling the gear housing to replace the switch component. HEADS UP Do not force the switch with pliers. You will break the plastic housing. The switch must be in the center (lock) position to change the battery.

Question 5

how do i clean out the vent slots on my bosch drill, it's full of sawdust after a drywall job.

Accepted Answer

DIAGNOSIS Sawdust and drywall dust are blocking the motor cooling vents on the gear housing. This causes overheating and premature failure. FIX Unplug the battery. Use compressed air from a can or compressor. Blow air directly into the long vertical vent slots near the motor. Angle the air flow to push debris out the back of the tool. Do not use liquids. IF THAT DIDN'T WORK For packed dust, use a soft, dry brush (like a paintbrush) to loosen it first, then use the air. Do not insert metal objects into the vents. HEADS UP Never submerge or spray cleaner into the vents. The motor and electronics are not sealed. Moisture will cause a short and permanent damage.

Question 6

drill seems weak, bogs down instantly driving a 2 inch screw into pine, feels like no torque.

Accepted Answer

DIAGNOSIS The electronic variable speed trigger or the motor control board is failing. It is not delivering full amperage to the motor. FIX First, rule out the battery. Test with a known-good, fully charged 12V Max battery. If problem remains, the issue is internal. The trigger/switch assembly (part 2 607 001 020) is the most common point of failure for power loss. IF THAT DIDN'T WORK The motor armature could have shorted windings. Check for a burning smell from the motor vents. A shorted armature (part 2 607 001 019) will cause severe power loss and heat. HEADS UP This tool has a 20+1 clutch. Make sure you are not in a low clutch setting (1-5). For drilling/driving, use the drill bit icon setting or the highest clutch setting (20).

Question 7

the chuck on my ps31-2a wobbles a bit when a bit is in it, makes holes not perfectly round.

Accepted Answer

DIAGNOSIS The keyless chuck's internal jaws or bearing race are worn or contaminated. This is common if the chuck is dropped or used with impact force. FIX This is a chuck assembly replacement. Part number is 2 607 001 017. You need a 10mm Allen key. Remove the screw inside the chuck (left-hand thread). Use the Allen key in the chuck jaws to unscrew the chuck from the spindle (right-hand thread). Install the new chuck and reverse the process. IF THAT DIDN'T WORK If wobble persists with a new chuck, the spindle itself is bent. This requires a full gear housing replacement. The tool is likely damaged from a severe drop. HEADS UP Always secure the bit fully. Insert it, hold the chuck collar, and tighten until you hear three distinct clicks from the ratcheting mechanism.

Question 8

my bosch ps31 drill driver just blinks a red light when i pull the trigger, no power at all.

Accepted Answer

DIAGNOSIS The battery pack is not communicating with the tool. The red status LED on the pack is flashing a fault code. FIX Remove the battery. Press and hold the battery fuel gauge button for 5 seconds. This resets the battery management system. Reattach it firmly to the tool until it clicks. Try the tool again. IF THAT DIDN'T WORK The fault is likely a bad cell group in the lithium-ion pack. You need a new 12V Max Bosch battery. The tool will not work with a permanently faulted pack. HEADS UP Do not try to disassemble or repair the battery pack. The lithium-ion cells are sealed and pose a serious fire risk if damaged.

Bosch 12V Max Drill Driver PS31-2A

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