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One morning recently, my battery was too weak to start Olga (a 240 DL wagon). I popped the hood and heard a buzz coming frome what I learned later was the Frequency Valve. The keys were in my hand, so I figured that is what had drained the battery.
There's a relay on the fender wall behind the coil from which I unplugged the connector, and the buzzing stopped, so I took off the relay and tested the terminals. The coil terminals read continuous, but the hot terminal (30) through to the output terminals also read continuous on both outputs (87 and 87a).
So I opened it up and tested with the switch in both the opened and closed position. Both positions resulted in continuity. This doesn't sound like any kind of relay I've ever seen, and nothing looked wrong with the guts of the thing ... but wait! Looking into the relay cover, I found a small strip of fabric. I took this strip and stuck it between the contacts that were closed in the relay's "relaxed" position and buckled the relay back up.
Plugged the relay back into the car and there was no buzz, so I got in and started her up. She's been running smoothly ever since.
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Hi David,
That was a nice piece of troubleshooting, but the part about continuity from input (30) to both outputs (87 and 87a) has me puzzled. That can't happen, with the unplugged relay in your hand, unless the relay has some kind of short.
In the early ('78-'81) Lambda relay 87 and 87a are common, but both are "normally open", meaning no connection to 30 until the relay is energized. Terminal 87 had Gray wire going to the Lambda ECU. Terminal 87a's Green wire went to the FValve.
From '82 on a different relay was used, with 87a now being "normally closed" (to 30) like you describe. But 87a was no longer common to 87, so 87 was the only energized output. Thus BOTH wires, Gray and Green, had to be fed from terminal 87.
My Puzzle:
Your description fits the later relay—power/continuity from 30 to 87a with relay deenergized. But the wires should [now] both be coming from 87. So with no internal connection between 87 and 87a I don't see how that "fabric fix" on 87a blocked the bogus voltage that was buzzing the FV.
Could you tell me the Bosch number on your relay? maybe 0-332-204-101?
Or a Hella with Volvo # 1259926?
And do the Gray and Green wires both come from terminal 87, with terminal 87a being empty?
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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This post has been marked as an answer to the original question.
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Well, that's what I said to myself, too. ("It can't happen unless..."), and that's why I opened it up to test it inside.
Inside, the two switch contacts are common. When the coil is de-energized, the switch plate contacts one leg of a U-shaped piece of metal. When it is energized the plate moves against the coil and the contact hits the other leg of the "U". The two legs represent 87 and 87a. Without some kind of insulation, there's no switch - the relay just goes from "on" to "on" on both terminals. So the insulator has to be in place for the relay to work, and it just fell out apparently. This is some piece of engineering, eh?
Your description of the different relays leads me to think that either someone has used a pre-82 relay in this beast and just hacked the guts of the relay to achieve the "off" condition, or that's how the relay was designed. Beats me. Maybe I'll poke around a junkyard to see if I can find what's inside another one. Or maybe I'll buy a new one, heh.
To answer your questions, though yes, there are two wires, grey and green on 87 and nothing to 87a (but as I noted, they are internally common). I don't know the brand. It says neither Bosch nor Hella, there's just a trademark that looks like an "S" superimposed on a ")(".
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I have relays with that mark but don't know the brand. Nor have I ever seen one that switched from On to On. Sounds like someone hacked it to work.
You "should" have the Bosch 0-332-204-101 (marked 20/30A), which switches between 87a and 87(with nothing wired to 87a).
The earlier (pre '82) 0-332-015-006 should work too. Although it's marked 2x15A, it did OK for years, powering the same fuel pump, FV, Lambda system, etc. The diagram on the side shows a 2 legged Armature ("switch plate") contacting separate 87 and 87b outputs when energized. With both of your output wires on '87, it will be just like the "correct" 101, but rated 15A rather than 30A.
It was also used for 240 power windows and '86+ Main headlight relay.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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