Re: Stubborn Vehicle

["David Teitelbaum" <jtrealty@xxxx>]

I think you are a little confused, The red/purple wire from the ECU is
a feed (not a ground). If you are measuring a voltage there then you
can assume the ECU is providing power to the frequency valve. If the
valve won't buzz it is either defective (possibly stuck) or the ground
wire is unattached or broken. Pull the plug on the frequency valve and
check the red/purple for power and the other wire for continuity to
ground. It is a short wire and is sometimes not hooked back up after
working on the fuel system. I don't think it is a very good thing to
ground the red/purple wire, it could damage the ECU. In general the
ECU doesn't fail. With incorrect troubleshooting procedures though I
guess you could damage it (grounding the red/purple wire would be one
possability). The most common problem is the lambda relay and then the
O2 sensor but I think you have ruled these out. You could put a 12
volt bulb across the wires at the plug for the frequency valve, it
should light dimly and fluctuate in brightness. 
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "cruznmd" <racuti1@xxxx> wrote:
> 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)