Hi Dave,

(a) Yes, LH2.0 corresponds to the B23F in 83 and 84 in US. The really really correct way to view that pink wire isn't available commercially. What you look for is the pink wire spends about half of its time near zero volts and the other half near 3.5 volts. Well, a slow trace on an oscilloscope would work, but you looking at the blinking numbers on a digital multimeter is close enough.

I implemented a transistor to switch an LED, mimicking the circuit in the LH2.2 ECU, because observing an LED going on and off is probably the best way to gauge the feedback loop.


But, it matters not how I do it, you can gauge the same thing using your DMM on the oxygen sensor lead. This method we use commonly and instinctively today was not available to the early 80's technician -- high input impedance digital multimeters were expensive. I show you the pink wire in the upper trace and the oxygen sensor in the lower trace below:



When Volvo published their technical manual covering this new system ca. 1982 the dealership network had a nifty do-all electrical instrument called the Mono-Tester. They suggested using its dwell meter function to monitor the pink wire. One could see the meter needle slapping back and forth at the rate of switching, but so many folks misinterpreted this slow, one-per-second observation of duty cycle as an actual dwell measurement being performed by the meter, which could not possibly integrate the slow transitions.

TL;DR... Just get used to monitoring the oxygen sensor, because this skill is transferable to all of LH. You can check back with the meter on the pink wire once you get the oxygen sensor switching.

(b) Yes, worthwhile. They are cheap.

(c) Don't be concerned. I've passed up my chance to own this treatise based on the reviews of knowledgeable hobbyists.

(d) Yes, a false air leak through the TB does seem at odds with what your current oxygen sensor is indicating. But you have to admit, the engine will not run without air, so knowing where it is coming from and that all is being measured by your new Fuel Injection Corp rebuilt AMM is important.

(e) Here is the best I can do showing you how to check for the air being passed through the idle air controller. Be sure it is working. It should be throbbing. Certain faults can cause it to lock in one position.



Blocking the path should allow you to stall the engine with the air bypass knob, eliminating the default air passed by the idle air valve with the idle test point grounded. Your Brickboard is your problem solver.
--
Art Benstein near Baltimore

Two secrets to keep your marriage brimming
1. Whenever you're wrong, admit it, 2. Whenever you're right, shut up.
-Patrick Murra