P0603moderate severityPowertrain
Internal Control Module Keep Alive Memory (KAM) Error
on 1998 Toyota Tacoma 2.7L I4 · RWD
What this code means
The PCM detected a fault with its Keep Alive Memory, which stores learned values and adaptations. This is usually caused by loss of battery voltage or an internal module fault.
Symptoms
- Check engine light on
- Loss of learned idle/fuel trims
- Rough running after battery disconnect
Common causes
- Weak or disconnected battery
- Corroded battery/ground connections
- Faulty PCM internal memory
- Poor wiring to constant power circuit
Diagnostic steps
- Check battery voltage and connections
- Inspect PCM constant power and ground circuits
- Clear code and retest for return
- Reflash or replace PCM if fault persists
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0004
Fuel Volume Regulator Control Circuit High
P0005
Fuel Shutoff Valve A Control Circuit/Open
P0005
Fuel Shutoff Valve A Control Circuit/Open