Electrical Tfi Electrical Testing Question

[DuderMcMerican]

Howdy,

A quick question on an electrical test chart cited in jrichker's tech notes, "How the TFI ignition works in 86-93 model Mustangs." JPEG of test chart attached.

Regarding test 3, "Power to TFI module, engine crank" I am getting around 10.6 volts, but the expected result is 8 - 10 volts. Is the excess 0.6 volts a problem? I imagine that it is otherwise the expected result wouldn't have given the specific range, but wanted to consult with y'all to make sure before I start messing with it.

Assuming that it is indeed a problem, the chart says that if it's not between 8 and 10 volts, then there's a "fault in the power circuit from the ignition switch." Where is the best place to start when looking for said fault? Start at the ignition switch and work back? Is voltage drop testing the way to go?

Thanks!

Edit: It occurs to me that voltage drop testing is probably the opposite approach to the problem I may be facing. Is there such a thing as voltage spike testing?

 

[jrichker]

Howdy,

A quick question on an electrical test chart cited in jrichker's tech notes, "How the TFI ignition works in 86-93 model Mustangs." JPEG of test chart attached.

Regarding test 3, "Power to TFI module, engine crank" I am getting around 10.6 volts, but the expected result is 8 - 10 volts. Is the excess 0.6 volts a problem? I imagine that it is otherwise the expected result wouldn't have given the specific range, but wanted to consult with y'all to make sure before I start messing with it.

Assuming that it is indeed a problem, the chart says that if it's not between 8 and 10 volts, then there's a "fault in the power circuit from the ignition switch." Where is the best place to start when looking for said fault? Start at the ignition switch and work back? Is voltage drop testing the way to go?

Thanks!

Edit: It occurs to me that voltage drop testing is probably the opposite approach to the problem I may be facing. Is there such a thing as voltage spike testing?

The excess.6 volts is nothing to worry about - it is less that 10% of the total range of volts.

 

[DuderMcMerican]

The excess.6 volts is nothing to worry about - it is less that 10% of the total range of volts.

That's a relief. Thank you!