Stubborn Vehicle

["cruznmd" <racuti1@xxxx>]

Yessir.

#5335 is the most stubborn car I have ever owned. It's enough to make
grown man cry. After all that care over the weekend with the guys, I
have yet another show-stopper (sort of).

Problem: The frequency valve is no longer working.

Please read carefully. There's a lot of info here. :)

Tests: 
1. Fuses 1 & 7 are good.
2. RPM relay is working. (pulled cover off and observed both contacts
closed when engine runs)
3. Lambda relay is working. Provides power to ECU correctly as noted
by voltage on green/yellow wire to ECU. ECU is grounded (cleaned &
checked)
4. Jumpered 87b to 30 on RPM relay to power lambda system. Valve does
not buzz.
5. 12Vdc is present on red/purp wire to freq valve. (grounded to block)
6. 12Vdc is NOT present across valve wires (red/purp & red/brn) The
ECU provides ground on red/brn. No ground appears present at any
time.(problem here?)
7. CO screw adjusted to encourage different behavior from ECU/freq
valve. No effect.
8. Valve does not buzz when WOT switch is closed (fixed ratio)
9. Valve does not buzz when engine is cold before O2 sensor kicks in
(fixed ratio)
10. Valve does not buzz when AA battery is applied to sensor lead.
11. I CAN open and close valve manually by providing ground from valve
(-) terminal to block since ground is missing from the ECU. Valve
operates. (I pretend to be the ECU this way by applying ground)
12. Dwell meter indicates no signal from ECU, reads zero. Tested IAW
the manual.
13. Lastly, cleaned and checked the lambda ground on the intake, and 
performed a continuity check on freq valve ground wire (red/brown)
from the ECU plug, to the freq valve. Wire is unbroken.

I'm always told the ECU's never fail. I have done everything I can to
avoid blaming the ECU. I have tried to eliminated the ECU as the
cause. I know I'm going to get flamed for this, but that's where this
seems to be leading. I believe the ECU switches ground on and off very
rapidly to make the valve buzz. The ground wire (red/brown) is intact
but the power circuit for the valve reads as an open when the system
is powered up. Again, the RED/PURPLE to the freq valve reads 12vdc, so
there is power. The ECU doesn't seem to be applying ground.

Am I crazy? Has ANYONE here ever had the ECU fail?

Thanks,

Rich A. &
The Stainless Steel Mule (#5335)