Using Coil + side as ign hot?
#1
08-06-2014, 11:47 AM
Using Coil + side as ign hot?
I have my MSD using the coil + wire as ignition switched, as per the MSD interface harness. The coil - goes to the MSD white/points wire.
Can I put a relay on this + wire to make an easy tap for underhood ignition on? Or would that draw too much current and upset the PCM? I figure a relay pulls 150 mA max and the coil had to pul more than that, but...
Can I put a relay on this + wire to make an easy tap for underhood ignition on? Or would that draw too much current and upset the PCM? I figure a relay pulls 150 mA max and the coil had to pul more than that, but...
#2
08-06-2014, 12:50 PM
The PCM grounds the coil to fire Magnet. The + side is always hot via the ASD relay so whatever you hook the relay to will switch via the ASD relay being energized, not the ignition switch.
The O2 downstream heater relay is hooked up on the same + wire via fuse "U" in the PDC.
It will not affect the PCM at all regardless.
The O2 downstream heater relay is hooked up on the same + wire via fuse "U" in the PDC.
It will not affect the PCM at all regardless.
Last edited by 00DakDan; 08-06-2014 at 12:53 PM.
#3
08-09-2014, 02:22 PM
#4
08-10-2014, 07:49 PM
#5
08-10-2014, 08:41 PM
Just in RUN (ON) or
From the FSM:
The ASD relay will be shut–down, meaning the 12–volt power supply to the ASD relay will be de-activated by the PCM if:
*the ignition key is left in the ON position. This is if the engine has not been running for approximately 1.8 seconds.
* there is a crankshaft position sensor signal to the PCM that is lower than pre-determined values.
From the FSM:
The ASD relay will be shut–down, meaning the 12–volt power supply to the ASD relay will be de-activated by the PCM if:
*the ignition key is left in the ON position. This is if the engine has not been running for approximately 1.8 seconds.
* there is a crankshaft position sensor signal to the PCM that is lower than pre-determined values.
#6
08-10-2014, 09:51 PM
Just in RUN (ON) or
From the FSM:
The ASD relay will be shut–down, meaning the 12–volt power supply to the ASD relay will be de-activated by the PCM if:
*the ignition key is left in the ON position. This is if the engine has not been running for approximately 1.8 seconds.
* there is a crankshaft position sensor signal to the PCM that is lower than pre-determined values.
From the FSM:
The ASD relay will be shut–down, meaning the 12–volt power supply to the ASD relay will be de-activated by the PCM if:
*the ignition key is left in the ON position. This is if the engine has not been running for approximately 1.8 seconds.
* there is a crankshaft position sensor signal to the PCM that is lower than pre-determined values.
