No start, CKP sensor 12v source?
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No start, CKP sensor 12v source?
Hi Guys, 2000 Expy 4.6 no start problem, no CEL.
Fuel pressure checked first its 36#. New pump & filter installed 5K miles ago.
Checking circuits following the Haynes manual, all is well until I get to the crank position sensor. Haynes wants 12v on one lead, I don't have it. The manual does not state the 12v source however looking at the wiring diagrams 12v for the CKP sensor seems to originate in the PCM.
PCM relay is functioning, fuses are good.
CKP sensor wires were hacked under the AC compressor, fixed that with a new plug/wires & threw a new CKP sensor in. Found another CKP wire hack job at the front corner of the valve cover. Wires twisted together & a glob of tape. Did not reconnect those wires yet but tested for voltage to them KOEO I get 1.56V on each wire no 12v.
I think I need a new PCM if I have the 12v source identified correctly.
What say the Ford Gurus?
Thanks for looking.
Fuel pressure checked first its 36#. New pump & filter installed 5K miles ago.
Checking circuits following the Haynes manual, all is well until I get to the crank position sensor. Haynes wants 12v on one lead, I don't have it. The manual does not state the 12v source however looking at the wiring diagrams 12v for the CKP sensor seems to originate in the PCM.
PCM relay is functioning, fuses are good.
CKP sensor wires were hacked under the AC compressor, fixed that with a new plug/wires & threw a new CKP sensor in. Found another CKP wire hack job at the front corner of the valve cover. Wires twisted together & a glob of tape. Did not reconnect those wires yet but tested for voltage to them KOEO I get 1.56V on each wire no 12v.
I think I need a new PCM if I have the 12v source identified correctly.
What say the Ford Gurus?
Thanks for looking.
Logistics Pro
Joined: Jan 2001
Posts: 3,740
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From: Central NYS
You can put your DVM on AC volts and put one probe on each wire (Polarity is not an issue.) When the engine cranks over you will see a small AC voltage if all is well. The faster the engine spins the higher the voltage. (The PCM is really looking at the Hz.)
Following alloro'a pin point test (
) will let you know if there is an issue with the hacked wiring.
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Thanks guys I'll work on it later today & post results.
Introducing 12v DC into an AC circuit made zero sense to me. If the Hanes manual is incorrect on this issue one has to wonder if there is other miss information.
Introducing 12v DC into an AC circuit made zero sense to me. If the Hanes manual is incorrect on this issue one has to wonder if there is other miss information.
Fleet Owner
Joined: Apr 2008
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For those of us that have been around a while, that goes without saying.
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