Too much voltage drop? - Updated
#988432
05/08/11 10:25 PM
05/08/11 10:25 PM
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Joined: Jan 2003
Posts: 559 Scottsdale, AZ
kenz
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 559
Scottsdale, AZ
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Car is a 73 Duster with a stock ignition system. Everything except the wiring harnesses is new (ign switch, module, dual ballast resistor, coil, distributor). With the car not running, but the ign switch in the run position, we have the following. (The Ammeter is bypassed)
Battery positive terminal: 12.20 volts Under dash bulkhead (blk & red wires): 12.06 volts Ignition switch connector + in (red wire): 12.01 volts Ignition switch connector run out (dk bl wire): 11.46 volts Engine side bulkhead connector (dk bl wire): 11.41 volts Dk bl into ballast resistor (both circuits): 10.53 volts Brown wire out of ballast: 3.26 volts Green wire out of ballast: 10.47 volts + side of coil: 3.21 volts
If I disconnect the + wire from the coil (module still connected) I get 11.2 volts at all connectors at the ballast resistor and at the coil.
If I unplug the module (coil connected) I also get 11.2 volts at the ballast resistor and the coil.
Is the drop at the ignition switch too much?
Is the drop caused by the coil and/or the ECM normal?
I assume 3 volts at the coil is too low since the car will not start unless I jump the ballast resistor. Do I have wiring issues?
Thanks in advance for any help. Ken
Last edited by kenz; 05/15/11 06:45 PM.
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Re: Too much voltage drop?
[Re: ahy]
#988437
05/09/11 09:02 PM
05/09/11 09:02 PM
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Joined: Jan 2003
Posts: 10,718 North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,718
North Dakota
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With nearly 12V at the coil with the key in the start position, I would think the car should start. As has been said the key in the start position basically 'jumps' the ballast resistor. How are you actually bypassing the ballast resistor to get a start?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Too much voltage drop?
[Re: 6PakBee]
#988438
05/12/11 05:58 PM
05/12/11 05:58 PM
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Joined: Jan 2003
Posts: 559 Scottsdale, AZ
kenz
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 559
Scottsdale, AZ
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Quote:
With nearly 12V at the coil with the key in the start position, I would think the car should start. As has been said the key in the start position basically 'jumps' the ballast resistor. How are you actually bypassing the ballast resistor to get a start?
It has the classic bad ballast resistor symptom. It wants to start while cranking but as soon as the key is let off to the run position it dies. Has to have something to do with the 3V at the coil when the key is in run position.
As for bypassing the ballast, I attached a jumper wire to the connectors instead of the ballast resistor. It'll start and run then. But I didn't check the voltage.
I haven't had a chance to get back to the car, hopefully this weekend. I'll definitely check the voltage while it's running.
Thanks again for all the help. Ken
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