fuel pump wont turn on,checked all relays and fuses, no spark,it cranks but wont start
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1998 Dodge Ram Van 1500 Question: how do i test camshaft sensor with multimeter
Answer #1lightsaber March 02, 2013, 11:55Technician
The ASD relay controls both the fuel injectors, and ignition system, and operates when the PCM gets the correct signal from the crankshaft position sensor. Start your testing with the ASD relay, and then the crankshaft position sensor. The CPS tends to fail frequently and cause intermittent rough running.
Replypushrod, March 02, 2013, 12:47Master
I agree, except asd should close/click with key on. They give a lot of trouble, also ecm provides the ground circuit to make it work. Have seen this circuit fail but that is just one scenario. Others possible! Can remove asd relay, turn key on, put relay back, does it click? Try it as many times as needed. Better way is a GOOD scanner to check this out!
Replycobracop29, March 02, 2013, 13:17Rookie
how do i test asd,camshaft sensor,crank sensor?
Replypushrod, March 02, 2013, 15:23Master
You stated already tested relays! Look at the reply to the first answer on how to check asd. No bus light on in dash??
Replylightsaber, March 02, 2013, 15:32Technician
ASD relay testing methods:
If you swap the ASD relay for another relay of the same type from an inconsequential circuit in your power distribution box you can basically confirm if the relay is good or not. By the book method follows:
Holding relay with terminals facing you (three across the top & two down) numbered from left to right then down: 86, 87A, 85, 87, 30
Terminal number 30 is connected to battery voltage.
For both the ASD and fuel pump relays, terminal
30 is connected to battery voltage at all times.
The PCM grounds the coil side of the relay
through terminal number 85.
Terminal number 86 supplies voltage to the coil
side of the relay.
When the PCM de-energizes the ASD and fuel
pump relays, terminal number 87A connects to terminal
30. This is the Off position. In the off position,
voltage is not supplied to the rest of the circuit. Terminal
87A is the center terminal on the relay.
When the PCM energizes the ASD and fuel
pump relays, terminal 87 connects to terminal 30.
This is the On position. Terminal 87 supplies voltage
to the rest of the circuit.
The following procedure applies to the ASD and
fuel pump relays.
(1) Remove relay from connector before testing.
(2) With the relay removed from the vehicle, use
an ohmmeter to check the resistance between terminals
85 and 86. The resistance should be 75 ohms +/-
(3) Connect the ohmmeter between terminals 30
and 87A. The ohmmeter should show continuity
between terminals 30 and 87A.
(4) Connect the ohmmeter between terminals 87
and 30. The ohmmeter should not show continuity at
(5) Connect one end of a jumper wire (16 gauge or
smaller) to relay terminal 85. Connect the other end
of the jumper wire to the ground side of a 12 volt
(6) Connect one end of another jumper wire (16
gauge or smaller) to the power side of the 12 volt
power source. Do not attach the other end of the
jumper wire to the relay at this time.
WARNING: DO NOT ALLOW OHMMETER TO CONTACT
TERMINALS 85 OR 86 DURING THIS TEST.
DAMAGE TO OHMMETER MAY RESULT.
(7) Attach the other end of the jumper wire to
relay terminal 86. This activates the relay. The ohmmeter
should now show continuity between relay terminals
87 and 30. The ohmmeter should not show
continuity between relay terminals 87A and 30.
(8) Disconnect jumper wires.
(9) Replace the relay if it did not pass the continuity
and resistance tests. If the relay passed the tests,
it operates properly. Check the remainder of the ASD
and fuel pump relay circuits. Refer to 8, Wiring Diagrams.