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Is there a way to test the ER stage other than swapping in another?
In this case, no. Most autoparts stores have a diagnostic service unit that can test the Power Stages, but the ones used in the 700/900 Volvos are not that common and are not included in the typical testing systems. Fortunately, a used Power Stage is aproximately $4 from a salvage yard.
If I need to get another, is the same one used for all 900-700 series and later 200-models?
I believe there may have been 2 different ones used, but even so, they may be interchangeable. Checking the part numbers against each other is a pretty bullet proof way to do it. Unfortunately, if the Power Stage has been replaced once already, it will usually be an off-brand like HUGO (rather than OEM Bosch) and does not have the same part numbers.
I have a spare AMM from my 84 240. Can I swap this one into my 760T to test?
No, don't even try it. Your '84 240 uses LH-Jetronic 2.0 fuel injection (commonly used in 82-84), and your '86 760 has LH-Jetronic 2.2 (common from '85-'89). The 2.0 systems use a Bosch 001 Air Mass Meter, and the 2.2 systems use a Bosch 007. There are an abundant supply of AMMs out there in the salvage yards and on eBay and typically cost about $35 uses. Just make sure the part numbers match and the Platinum wire inside isn't broken.
It seems strange that the coil is not putting out electricity to the primary wire. I believe it is the ER stage that supplies juice to the coil. Perhaps I have a bad wire? If I recall correctly, there are two small wires leading to the coil. The wire harness is a bit of a mess. Should I be able to detect electricity to one of these posts with a multimeter upon cranking?
If the Key is in the "ON" postion (position 2), you should have +12 volts at both input terminals of the coil. The power stages grounds out one side of the circuit and completes the electrical path, but only at the command of the ignition timing controller (which is getting it's information from the Hall-Effect sensor). Before continuing further, get out your multi-meter and check the resistance of the Primary and Secondary windings of the Ignition Coil, and also check the resistance of the wire from the coil to the distributor cap. Compare these against the values listed in the service manual you're working from. (If you don't yet have one, purchase the Haynes book to start with and later get the Volvo Green manuals. Chiltons is useful only for warming yourself in the winter by burning it.)
And, I can't seem to find the radio suppression relay. Can you give me a hint?
You may not have one. Your Fuel Injection Relay could be supplying power for the entire fuel system without the use of a seperate Radio Supression Relay. Some of the early 740/760 vehicles were fitted with the RSRs at the dealerships, some came fitted on the assembly line, but it wasn't until the late 90s that they were standard on all 700/900 vehicles.
Why not put it with all the other relays under the ashtray?
Not practical. They were added mid-production and the idea is to keep the power path for the Fuel Injection system AWAY from the radio console and reduce the Electromagnetic Interferance received by the radio. -thus hence the name "Radio Supression Relay."
God bless,
Fitz Fitzgerald.
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'87 Blue 240 Wagon, 255k miles.
'88 Black 780, PRV-6, 148k miles.
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