Ignition transformer capacitor issue
Senior Member
Joined: Mar 2021
Posts: 4,798
Likes: 2,396
It is a Capacitor to ground from the 12 volt source for the coils and often for the fuel injectors.
They are often on both banks to reduce RF interference that normally can result from a collapse of a high voltage magnetic field.
The result, if not used, can radiate interference to other circuits in the wire harness and near by functions.
These Capacitors have been used in FI applications since from back in the md 80s.
It usually results in a blown supply fuse or disabling the DC supply to the Coils and or Fuel Injectors.
They absorb the high voltage kick for the same reason there was a Capacitor in the old time Points and Condenser Distributer that lengthened the life of the Points.
Sometimes a Diode is used across individual parts supply to kill the reverse high voltage spike that occurs in a coil winding by monetarily shorting the path >after< the part has done it's job but not disable the power source.
If either of these devices short circuit >fail<, it stops the function.
Sorry for the long reply but you asked and I described what and why.
Good luck.
They are often on both banks to reduce RF interference that normally can result from a collapse of a high voltage magnetic field.
The result, if not used, can radiate interference to other circuits in the wire harness and near by functions.
These Capacitors have been used in FI applications since from back in the md 80s.
It usually results in a blown supply fuse or disabling the DC supply to the Coils and or Fuel Injectors.
They absorb the high voltage kick for the same reason there was a Capacitor in the old time Points and Condenser Distributer that lengthened the life of the Points.
Sometimes a Diode is used across individual parts supply to kill the reverse high voltage spike that occurs in a coil winding by monetarily shorting the path >after< the part has done it's job but not disable the power source.
If either of these devices short circuit >fail<, it stops the function.
Sorry for the long reply but you asked and I described what and why.
Good luck.
Thread Starter
Member
Joined: May 2013
Posts: 51
Likes: 10
THANK YOU SO MUCH for that reply!! Seriously.
My truck shut down on me about 3 weeks ago. 2021 with the 5.0. Would only turn over and would not crank. Fuse 9, under the hood was practically melted. I think it was Fuse 9.
They first thought it was a coil issue, but then decided it was this capacitor issue. I bought the truck with 21,000 miles on it and the history showed the previous owner had the same "shut down" as I did. The mechanic, then, replaced a coil. 11,000 miles later it does it to me. I've been scratching my head ever since.
NOW, I can't decide to buy the Premium Care extended warranty or trade in the truck, as I am now nervous about going very far in it. I shouldn't have to feel that way, but I do.
Again, Thank you. Any advice you can give me, I'd appreciate it a lot!!!!
My truck shut down on me about 3 weeks ago. 2021 with the 5.0. Would only turn over and would not crank. Fuse 9, under the hood was practically melted. I think it was Fuse 9.
They first thought it was a coil issue, but then decided it was this capacitor issue. I bought the truck with 21,000 miles on it and the history showed the previous owner had the same "shut down" as I did. The mechanic, then, replaced a coil. 11,000 miles later it does it to me. I've been scratching my head ever since.
NOW, I can't decide to buy the Premium Care extended warranty or trade in the truck, as I am now nervous about going very far in it. I shouldn't have to feel that way, but I do.
Again, Thank you. Any advice you can give me, I'd appreciate it a lot!!!!
Senior Member
Joined: Mar 2021
Posts: 4,798
Likes: 2,396
If you have replaced the part and the fuse, I would say your good for a long time.
The engine usually will run without the Capacitor but may have radio or audio interference as a result.
What happens is the reverse voltage kick from Coils' operation is very high and breaks down the Capacitor internal insulation, as sort of a sacrifice.
Sometimes in some circumstances, the failure, if the Cap goes open, the spike voltage interference can get back to the PCM on other leads and cause 'havoc' with processing that can result in drivability problems.
Doesn't happen very often but like any other part, sometimes there is a failure.
The fuse blows to prevent the wire harness from starting a fire from a lead that turns red hot before melting, at some point.
Also never replace a fuse with a higher current value, just for that reason.
I would not trade the truck for this unless you want to, bad enough.
Good luck.
The engine usually will run without the Capacitor but may have radio or audio interference as a result.
What happens is the reverse voltage kick from Coils' operation is very high and breaks down the Capacitor internal insulation, as sort of a sacrifice.
Sometimes in some circumstances, the failure, if the Cap goes open, the spike voltage interference can get back to the PCM on other leads and cause 'havoc' with processing that can result in drivability problems.
Doesn't happen very often but like any other part, sometimes there is a failure.
The fuse blows to prevent the wire harness from starting a fire from a lead that turns red hot before melting, at some point.
Also never replace a fuse with a higher current value, just for that reason.
I would not trade the truck for this unless you want to, bad enough.
Good luck.
5 Year Member
Joined: Dec 2018
Posts: 4,446
Likes: 1,195
From: Ocean Springs MS
125,
It’s been more than a year since you last posted. Have you resolved this issue and if so, please post the solution? Feedback is important so that we all learn solution paths to these issues.
Thanks in advance
Jimboy
It’s been more than a year since you last posted. Have you resolved this issue and if so, please post the solution? Feedback is important so that we all learn solution paths to these issues.
Thanks in advance
Jimboy