Testing Crankshaft Position Sensor voltage
08-06-2017, 04:17 PM
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Testing Crankshaft Position Sensor voltage
1999 F150 XL, 4.2L engine, manual trans.
Engine turns over but doesn't start.
Following the Haynes manual, this has been my diagnostic trail:
- No spark at plugs
- Checked for 12V at ignition coil connector, GOOD
- Checked for 12V pulses at the coil connector when cranking engine to verify trigger signal to coil, NO SIGNAL
- Checked for battery voltage to crankshaft position sensor (CKP), NO VOLTAGE
Haynes is not clear as to what to do if there's no power at the connector.
Here's what I'm thinking:
a) I may be testing the CKP connector improperly for voltage. I've made a thin pin to go into each of the 2 connector sockets and hooked my 12V test light to battery neg. With the key ON, I couldn't get any voltage reading from either socket. Should I do this differently?
b) There may be a bad wire somewhere in the system. The wiring diagram in the book tells me that this connector goes straight to the computer (PCM), but it doesn't ID the exact pins. If I knew that, I could check for continuity at least.
Any other paths to follow?
Thanks in advance,
Tom
Engine turns over but doesn't start.
Following the Haynes manual, this has been my diagnostic trail:
- No spark at plugs
- Checked for 12V at ignition coil connector, GOOD
- Checked for 12V pulses at the coil connector when cranking engine to verify trigger signal to coil, NO SIGNAL
- Checked for battery voltage to crankshaft position sensor (CKP), NO VOLTAGE
Haynes is not clear as to what to do if there's no power at the connector.
Here's what I'm thinking:
a) I may be testing the CKP connector improperly for voltage. I've made a thin pin to go into each of the 2 connector sockets and hooked my 12V test light to battery neg. With the key ON, I couldn't get any voltage reading from either socket. Should I do this differently?
b) There may be a bad wire somewhere in the system. The wiring diagram in the book tells me that this connector goes straight to the computer (PCM), but it doesn't ID the exact pins. If I knew that, I could check for continuity at least.
Any other paths to follow?
Thanks in advance,
Tom
