obd2 code 1633
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obd2 code 1633
I have a 1999 ranger extended cab sport, 2wd, 3.o liter flex fuel engine, auto. Using an OBD II scanner shows a pending P1633 (keep alive memory power voltage too low). It has shown this continuously for the last two years. It is due have an emission check and the computer will have to show ready in order to pass. Right now, it will not pass. The battery terminals are clean and secure and the battery was replaced two months ago. I had gone through many start cycles before the battery was replaced and after but the pending code remains. Because the code is pending, the light never comes on. What should I be looking for?
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Joined: Dec 2001
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From: South Jersey
Welcome to FTE!!!!
QB1 CHECK BATTERY TERMINALS
NOTE:
If KAPWR is interrupted to the PCM (that is, when a breakout box is installed or the battery is disconnected), DTC P0603/P1605 can be generated on the first power-up.
l Inspect the battery cables for loose connections, corrosion.
l Are the battery terminal connections in good condition?
Yes
KEY OFF. Battery terminals are OK. GO to «QB2».
No
REPAIR battery terminals as necessary.
QB2 INSPECT ENGINE COMPARTMENT FOR PROPER WIRE ROUTING
l Inspect Electronic Engine Control (EC) System wiring for proximity to ignition components or wires.
l Is wiring too close to ignition components or wires?
Yes
REROUTE as necessary.
No
Engine compartment wire routing is OK. GO to «QB3»
QB3 CHECK KEEP ALIVE POWER (KAPWR) TO PCM
NOTE:
Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
l Disconnect PCM.
l Measure voltage between KAPWR circuit at the PCM harness connector and ground.
l While observing digital multimeter, grasp the Electronic EC harness and wiggle, shake or bend a small section while working from the PCM to the dash panel.
l Does the voltage reading indicate less than 10.5 volts?
Yes
ISOLATE and REPAIR open circuit.
No
No open in KAPWR harness circuit detected. GO to «QB4».
QB4 CHECK FOR REPEAT OF DTC P0603/P1605/P1633
l Reconnect PCM.
l Start engine and allow it to reach operating temperature.
l Run Key On Engine Off Self-Test.
l Retrieve Continuous Memory DTCs.
l Is DTC P0603, P1605 or P1633 present?
Yes
REPLACE the PCM.
No
REPAIR other DTCs as necessary. If none, testing is complete.
QB1 CHECK BATTERY TERMINALS
NOTE:
If KAPWR is interrupted to the PCM (that is, when a breakout box is installed or the battery is disconnected), DTC P0603/P1605 can be generated on the first power-up.
l Inspect the battery cables for loose connections, corrosion.
l Are the battery terminal connections in good condition?
Yes
KEY OFF. Battery terminals are OK. GO to «QB2».
No
REPAIR battery terminals as necessary.
QB2 INSPECT ENGINE COMPARTMENT FOR PROPER WIRE ROUTING
l Inspect Electronic Engine Control (EC) System wiring for proximity to ignition components or wires.
l Is wiring too close to ignition components or wires?
Yes
REROUTE as necessary.
No
Engine compartment wire routing is OK. GO to «QB3»
QB3 CHECK KEEP ALIVE POWER (KAPWR) TO PCM
NOTE:
Refer to the PCM connector pin numbers in the beginning of this pinpoint test.
l Disconnect PCM.
l Measure voltage between KAPWR circuit at the PCM harness connector and ground.
l While observing digital multimeter, grasp the Electronic EC harness and wiggle, shake or bend a small section while working from the PCM to the dash panel.
l Does the voltage reading indicate less than 10.5 volts?
Yes
ISOLATE and REPAIR open circuit.
No
No open in KAPWR harness circuit detected. GO to «QB4».
QB4 CHECK FOR REPEAT OF DTC P0603/P1605/P1633
l Reconnect PCM.
l Start engine and allow it to reach operating temperature.
l Run Key On Engine Off Self-Test.
l Retrieve Continuous Memory DTCs.
l Is DTC P0603, P1605 or P1633 present?
Yes
REPLACE the PCM.
No
REPAIR other DTCs as necessary. If none, testing is complete.
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Sorry it took so long to reply. I did not have a wiring diagram to show which wires in the harness went where and was unable to locate the hot wire. I took it to an auto repair shop that is state certified in advanced emission diagnostics, according the state manual I received when the truck failed the emissions. It turned out there was a broken wire in the harness, the hot wire. Rather than replace the harness, they ran a new hot wire along the outside of the harness. Now the computer reads ready and it passed.
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