Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
DTC P0603
P0605
PCM Keep alive memory (KAM) test error
PCM Read only memory (ROM) test error
DESCRIPTION
• DTC P0603 indicates PCM Keep Alive Memory (KAM) error
• DTC P0605 indicates PCM Read Only Memory (ROM) error
[Possible Cause]
• Battery terminals corrosion or loose connections • Harness open in keep alive power circuit
• Improper keep alive power circuit wire routing • Damaged PCM
STEP INSPECTION
ACTION
1 CHECK BATTERY TERMINALS
Note
• If Keep Alive Power (KAPWR) is
interrupted to PCM (i.e. when breakout box
is installed or battery is disconnected), DTC
P0603 and/or P0605 may be generated on
first power-up.
• Inspect battery cables for loose
connections, corrosion, etc.
• Are battery terminal connections in
good condition?
Yes Go to next step.
No
SERVICE battery terminals as necessary.
RERUN OBD Test.
2 INSPECT ENGINE COMPARTMENT FOR
PROPER WIRE ROUTING
• Inspect PCM wiring for proximity to ignition
components or wires.
• Is wiring too close to ignition
components or wires?
Yes REROUTE as necessary.
RERUN OBD Test.
No Engine compartment wire routing is okay.
Go to next step.
3
CHECK KEEP ALIVE POWER CIRCUIT TO
PCM
• Key off.
• Disconnect PCM. Inspect for damaged or
pushed out pins, corrosion, loose wires,
etc. Service as necessary.
• Install breakout box. Leave PCM
disconnected.
• Measure voltage between Test Pin 55 and
Test Pin 51 or 103 at breakout box.
• W hile observing DVOM, grasp PCM
harness and wiggle, shake or bend small
section while working from PCM to dash
panel.
• Is voltage less than 10.5 volts?
Yes ISOLATE and SERVICE open in keep alive power circuit.
REMOVE breakout box.
RECONNECT PCM.
RERUN OBD Test.
No No open in keep alive power circuit harness detected.
REMOVE breakout box.
RECONNECT PCM.
Go to next step.
4 CHECK FOR REPEAT OF DTC P0603/P0605
• Activate KOEO self-test.
• Is DTC P0603/P0605 retrieved?
Yes REPLACE PCM.
RERUN OBD Test.
No SERVICE other DTCs as necessary.
If none, testing is complete.
DTC P0603/P0605 was due to previous service action
mentioned in step 1.
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