causes for a non-functioning FV???(4ktq)

[Marc Swanson]

Hi Orin!,

> There is more than one ground to the ECU - pins 34, 18, 6 and 9 at least.

I verified good ground to 9 and 18. 6 and 34 have NO path to ground either
with ignition on or off.  My bentley shows pins 6 and 34 going to brown
stripped wires to ground connection 91 which is "welded -1- wiring harness,
electronic ignition".  Perhaps this may be the culprit???  Where is ground
connection 91?  Why are they stripped wires?  are they switched with
something?

> Also make sure pin 2 gets a good ground through the ignition booster
> or strange things can happen.

Hmm... I checked pin 2 vs a solid ground and I got 1.77 ohms.  Is this
acceptable or too high?  Additionally I got .654 ohms between pins 2 and 22
(the two wires going to the ignition booster).  Where does the ignition
booster get its ground from?


> What is the resistance of the frequency valve?  Has it gone open/short?

No.  The FV itself is fine.  I don't recall the actual resistance value, but
Nate measured that and mentioned it was ok I believe.  Irregardless I don't
see a duty cycle of 50% at the CO tap which tells me something is up.  Your
2 first comments had me rushing out to the garage since I hadn't checked
either of those.  I think you are on the right track....

Thanks!



-Marc-