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Ign ECU Q... Where is my start/run voltage going??
#1291661
08/26/12 02:44 PM
08/26/12 02:44 PM
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Joined: Jul 2006
Posts: 139 MA
limelight440
OP
member
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OP
member
Joined: Jul 2006
Posts: 139
MA
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440 w/ MP orange box (ballast ohms ~1.6) Car is hard starting, has been for some time. WOULD A BAD ECU CAUSE EXCESSIVE DRAW ON START & RUN CIRCUITS??? I take the following readings without my clutch safety switch pressedi in (no starter).
With both ballast resistor leads removed, the run side gets 12v with ign switch in run & the coil side gets 12.5v when ign switch is in start
plug the leads to the resistor though, and RUN is only getting 5v(AT COIL) or so & START is only getting 11v(AT COIL)
What I have been doing, is unplugging one connector from the ballast resistor. This allows the engine to fire (start) but not run. Once the cylinders fire, I plug in both sides of the ballast & the engine starts & runs.
NOTE: When I unplug the ECU, all voltage readings are as would be expected across the ballast & at the coil.
Last edited by limelight440; 08/26/12 03:45 PM.
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Re: Ign ECU Q... Where is my start/run voltage going??
[Re: limelight440]
#1291666
08/26/12 04:28 PM
08/26/12 04:28 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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When measure voltages with no load (connector unplugged) you should read battery voltage, you are not.
When reading voltage with a load (connector plugged in) you are reading low voltages. Your problem isn't the ECU, it is the supply to the ballast/coil/ECU. Clean up and tighten all you connections, take a voltage measurement at each connection to see where the loss is. I usually start at eh bulkhead connector as that is usually the culprit.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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