Coil problem?

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
6,026
Reaction score
2,039
Location
Rib Mountain (Wausau) WI
If you have electronic spark control or lean burn, you are correct. You may want to check the charging system voltage at 2,000-3,000 rpm, to make sure it isn't going too high while driving. It shouldn't go above 14.6 volts max. Above 14 volts at idle is unusually high. Not sure what coil you installed but, does it have printing the side saying "no resistor required" or "External resistor required", or something similar to that? As long as the coil is rated for 12-14 volts constant (no resistor required) the 14 volts is fine. If it requires a resistor, it's made to operate on 7-8 volts (12 volts in "start"), supplying it with 12-14 volts constantly can cause it to overheat and fail.
 

69-

Well-Known Member
Joined
Dec 13, 2020
Messages
183
Reaction score
92
Location
Germany
Fast blinkers? Whats the voltages in your system?
E.g. ground to alternator output stud and in comparison directly at the battery?
 

AJ/FormS

Well-Known Member
Joined
Apr 26, 2016
Messages
1,272
Reaction score
298
Location
On the Circle of the earth, Southern Man,Canada
Fast blinking is not due to over-voltage. Let me rephrase that; I have not seen 14.2volts be a problem. Lots of cars nowadays have charging systems running ~14.2 volts; it is actually quite common.

Fast blinking is usually due excessive draw in the bulb circuit , in the which, the hi-draw causes the bi-mettalic bar inside the old-style flasher to heat up too fast, and then she breaks contact.
The hi-draw could be from wrong bulbs, too many bulbs, faulty bulbs, or a plain old short somewhere including inside the bulbs them selves.

But that old-style flasher eventually just gets worn out.
You can try replacing it with a "HD electronic type" sometimes called a trailer flasher which does not suffer the same malady.
I have seen the short inside the signal switch.
 
Last edited:

SharkHead

Well-Known Member
Joined
Jan 12, 2020
Messages
55
Reaction score
0
Location
Polk County FL
At rpm rev I am getting 14.4v from the coil and 14.6v from the main post on the alternator.
The coil is an original mopar 4176009.
 

Aspen500

Well-Known Member
Joined
Feb 14, 2015
Messages
6,026
Reaction score
2,039
Location
Rib Mountain (Wausau) WI
That voltage is perfect. 14.6 volts is the what the regulator limits voltage to on conventional (non-computer controlled) systems.
 

Hayzoos

Well-Known Member
Joined
Aug 9, 2020
Messages
73
Reaction score
19
Location
Revloc, PA
With the Spark Control Computer (Lean Burn) the voltage is controlled on the (-) negative side of the coil from inside the computer. With the electronic ignition the ballast resistor controlling the voltage is on the (+) positive side of the coil. So testing the voltage at the (+) positive side of the coil and the other voltmeter lead grounded is correct for the electronic ignition with a ballast resistor. The equivalent test point with the Spark Control Computer is in the computer so is not as easy to perform. But if you connect the voltmeter to the battery (+) positive and the (-) negative of the coil you should get a proper reading of voltage at the coil on the Spark Control Computer lean burn system. I haven't tested this but the voltage should be in the same range of 6-8 volts. I came up with this by examining the FSM wiring diagrams and knowing that the same external resistor required spec. coil is used in both systems.

The Spark Control Computer lean burn system has the equivalent of a ballast resistor inside the computer. It starts with a direct ground or a higher voltage and runs with a resisted ground or a lower voltage.

They do not generally build resistors into coils. Resistors create heat and excess heat is bad for coils. The coils that run at battery voltage have different windings so the primary can handle the higher voltage. This also means they have different secondary windings to match the primary windings so the resulting secondary voltage is in the proper range for ignition and not too much which would wear away plug electrodes faster.
 
Top