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I have a POS Haynes manual for a 1981 240 turbo. I am trying to trace down a wiring problem. My freg. valve is not working right, I think. I traced everything back to the freq. valve relay. I think I should have two voltage connections at that relay. One powers the relay. The other is the voltage to the relay that, when the relay is energized, supplies power to God knows where. I have the voltage that is switched at the relay and and goes wherever. I do not have the voltage that turns it on. I traced the wires back to the fuel pump relay. For some reason I think both wires that power the freq. valve relay are grounded. I don't really know what is going on. My haynes manual sux and is not accurate. Where does the freq. valve power come from and go. I need as much info as possible. FYI: I have a degree in electrical engineering so you can be very technical with me.
One last thing: I have a very rich condition. The car runs but not well. Please help.
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In case anyone else did'nt post this, you can get the official volvo wiring manual from volvotechinfo.com . A very good investment. I recall the price being very reasonable and extremely fast shipping. I got my manual in two days.
--
Paul NW Indiana '89 740 Turbo 103,000
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Sorry,don't have a scanner,Here's a picture.If it doesn't show I'll post one to the gallery
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Damn low res hosting! If you want a better one email me and I'll shoot it your way.The picture looks clearer than that mess!
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So your car is running real rich. Let's start with the basics:
Main engine wiring harness okay? If no, all bets are off until you replace it.
Does your mileage improve with the lambda relay and/or the frequency valve unplugged? If yes, see below.
Is your frequency valve buzzing? If yes, the relay is probably okay.
How old is your oxygen sensor, and what condition is it in? If it's old, of unknown age, and/or looking funky.. replace it. It's a $10-$30 part. If that doesn't solve anything, pop open the relay and look for cracked soldering.. fix or replace (cheap either way).
I've got the wiring diagram manual (prelim model year 85) behind me. I'm waiting for the !$@! USPS to deliver the (K-Jet, IRS, Laycock OD) manuals I've “ordered”. No scanner, but I don't think you really need an EE degree to diagnose K-Jet (altho it is a royal pain if you ask me).
I feel your pain. My sedan needs both fuel pumps to be replaced (or so it seems by the god awful noise at a full tank). However, I've managed to make it run far worse by tinkering with the #1 injector (and still having not managed to separate the holder from the injector. At least with LH-Jet, the injectors are rebuildable and easy to remove.
- alex
'85 244 Turbo
'84 245 Turbo
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Sorry,cell # might help huh,.... 541-410-0359 Ore. In the length of time it took me to type this I see two others already offered help. That the great thing about this board ! Tom
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Doc, I've got volvo wiring diagrams for the B21F-turbo and a volvo fault tracing service manual that troubleshoots the oxygen sensor / frequency valve. Good book, I have used it with success.
You are correct about two B+ supplies to that relay. According to the turbo diagram, the relay has the standard terminals... #30 (red) (hot all the time) rt. from the battery terminal block on the fender. Not fused. #86 (blue), comes from terminal 87b on the fuel pump relay. (87b also has a blue wire that goes to, and powers, control pressure reg.) #85 (black), goes to ground. #87a has a green wire and a gray wire leaving it. Green goes to one side of frequency valve, other side of freq. valve is brown and goes to ECU ter. #15. Gray wire goes to ter. #8 ECU.
Activation of the relay is by B+ from ter. 87b on the F.P.Relay. B+ goes through the coil out to ground via ter. #85 blk. B+ from #30 then goes through relay and out #87a to the freq. valve and ECU.
The system testing is carried out in the Fault Tracing manual that I told you about. It is only 20 pages, and I can certainly copy and send to you. The only problem is that I will be at a firearms trade show all weekend. I can copy and send out on Monday but not before. Do you have a fax # ? If I have not explained clearly, and this cannot wait until monday, I will take the books with me to the show and you can try and call (you know how cell phones can be). HTH, Tom
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Never seen one of these but I have a manual showing the lambda system in the turbo, though it might be later version. It shows a form A relay switching unfused battery to one side of the frequency valve's solenoid when a blue wire brings fused battery from the normally open contact of the fuel pump relay (likely suspect?). The other side of the freq valve solenoid is brought near ground by the collector of a switching transistor within the "lambda brain" or as the manual refers, control unit.
I will try to scan and email.
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Art Benstein near Baltimore
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You just had to one-up me with that switching transistor crap, didn't ya! If you have a diagram that is that detailed please send me a copy as well. All my diagram shows is all these wires going into a "black box" and I was just guessing that something was switching a ground (at proper fx) to the freq. valve...
Justin B.
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Well, I didn't set out to-- we were replying at the same time, but you arrived first while I was still adjusting my glasses.
I've been making maps of most of the relays and so forth, but this wasn't one of them, just the usual Volvo symbology with a transistor in the box showing the open collector output of the "black box". Often these abbreviated in/out terminal designations are mistaken in the service literature. Can't rely on it. But in this case, how else would the lambda controller operate the gas valve...
That email I sent Doc was over a meg- sure you want it? I could tell he had cable.
--
Art Benstein near Baltimore
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I wasn't thinking about the relay, the "black box" I was referring to was the control unit/module. Do you have diagrams of the internal workings of the control module? If not, my wiring diagram should suffice. I have a pretty decent wiring diagram from friends "mitchell on Demand" system.
It makes sense that the control unit/module probably would use a transistor (or maybe darlington pair) to gate on and off with a varying pulse width determined by the associated O2 sensor circuitry. Whether the frequency valve is on the collector or emitter side I suppose doesn't affect our musings here...
Time to call it a day before my posts start to make less sense than they normally do! ;-)
Justin
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I also meant the control unit, but this isn't an "internal" schematic with all the parts. It is a schematic in the sense that all volvo's literature depicts the black boxes, with ins and outs represented well enough for someone to determine if the thing is working, not to fix it, just to replace it. Anyway here is a section small enough to post.
--
Art Benstein near Baltimore
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According to the wiring diagram (Mitchell on Demand) for a 1984 a brown wire goes back to the computer module and a green wire goes to the O2 relay (looks like terminal 87B) and also the module... The other connections to the O2 relay are black (ground), red (+12v), and blue which goes to the fuel pump relay.
Just looking at the diagram (and being a 20 year out of practice bench tech) it looks like maybe the fuel pump relay (when closed) supplys +12v to the O2 relay which in turn might put +12v to the module and freq. valve while the other wire to the freq. valve from the computer might supply a variable frequency "ground" depending on o2 sensor reading?
Good luck,
Justin B.
83 Turbo
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