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I have been having starting problems with my 90 240. From your help I have determined that the fuel pump relay is not the problem. I ran a jumper from #4 to #6 fuses and it starts fine. I replaced the relay and I have the same problem. I pulled the ECU and I do have the dreaded 561 ECU. Is there a fix to the ECU or should I just buy another one? Which ECU should I buy? Also, this may be nothing, but the fuel gauge now does not work...
Thanks!
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Don't overlook the crank sensor
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I ran a jumper from #4 to #6 fuses and it starts fine.
That's agood test, but it doesn't prove the relay is good. The jumper puts voltage where the FP relay *should* (but didn't).
So if it ran with the jumper, that proves the Ignition is good—and your jumper substituted for the failing relay. "Failing" in the sense that it probably wasn't energized by the ECU, as Art explained in his post.
Gotta go try to unfreeze a neighbor's pipes now, but will check back.
Bruce
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67
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There's a yellow-black wire that originates at ECU pin 21 and runs to the fuel pump/main relay at terminal 86/1. This supplies the ground return for the fuel pump half of the relay if and only if ignition pulses are recurring.
If your 561 ECU is not doing its job, the ground will not be supplied to the relay. Use a ground referenced test light here, and depending on the lamp in the test light, it will either light up, allow the pumps to run or both. This terminal yellow-black wire needs to be a steady ground. Better yet, just run a jumper to ground temporarily. If the car runs normally, you need a new ECU. The ECUs with -951 part number have this common trouble repaired, or rather re-engineered, so that is your best bet for a replacement.
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Art Benstein near Baltimore
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Hi Art,
I need some enlightenment on the LH 2.4 I guess. I'm inclined to (dare I say it ) ... argue, no-quibble, er ah question the following:
There's a yellow-black wire that originates at ECU pin 21 and runs to the fuel pump/main relay at terminal 86/1. This supplies the ground return for the fuel pump half of the relay if and only if ignition pulses are recurring.
I thought the "ground return for the fuel pump half..." was via the Blue/Green wire at 86/2, via ECU pin 20.
I see the Y/B wire as the ground-pick for the Main Relay, which powers the + side of the Fuel Relay coil. Am I putting too much faith in the Bentley diagrams???
Or—more likely—just having another senior moment?
Bruce
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67
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Bruce, I need to plop 2.5 diopter magnifiers on top of the 1.75's I walk around with to see that section of Bentley's schematic, so undoubtedly I had the Senior Moment, not you. To make matters worse, my better half moved my computer and bookshelf into the basement, and the lighting has not yet been improved to presbyoptic requirements. But enough excuses, I apologize for the bum steer and I'll begin to look for a green book WDM for one of the later models-- they're so much easier on my eyes.
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Art Benstein near Baltimore
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Art,
My lookers need gobs of augmentation too. Always have a glass in hand when in the diagrams (compounding my problems?). Anyhow, I forgot to ask—which ground does the "bad" ECU fail to provide? The Y/B to the Main relay? Or the BL/GN to the Fuel relay?
And can the proper ground jumper override this fault (along with the safety aspects)? I've suggested the BL/GN a time or two, but now I'm not sure, since either one could mean a no-start
Bruce
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67
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posted by
someone claiming to be Dharvey
on
Sun Jan 11 14:12 CST 2004 [ RELATED]
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Art--
Thanks for the so informative photos. As one driving on a replacement 561, now I want to know whether I'm relying on an early or late production box.
But I hate to open up anything auto-electronic if it isn't really necessary. It's just asking for trouble.
If you ever hear of a code distinction or other distinguishing birthmark, please post it. Sure seems like Volvo would have wanted a code distinction so THEY could keep their late production separated from the older.
Hmmm. Does anyone know which year models got the updated 561s? Maybe everything after a certain chassis number?
Doug Harvey
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Doug
I would also like to know if later year 561 ECU's were "fixed" or are they also prone to the ground failure. You may want to post this question as a new message. Dan
--
85 245 M46 189K, 92 245 A70 116K
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posted by
someone claiming to be Dharvey
on
Sun Jan 11 15:59 CST 2004 [ RELATED]
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In the post previous to mine. He said that there was a mid-production change in the 561s that improved the durability of this circuit, even before the change over to the 951.
The problem is, he doesn't know any way to tell which type a particular unit is except to pop the hood and look at the circuit layout--hence the side-by-side photos, which are great and make it easy to tell which type you've got.
But it would be even easier to know from chassis number or a code stamp on the cover which type it is. Better than opening up anything electronic.
Doug Harvey
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Yes but I would like to know if my 92 is updated. Dan
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85 245 M46 189K, 92 245 A70 116K
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Hi Art,
I been squintin' again — knew you could hardly wait — and must respectfully take issue with the following:
"The other pin, #21 runs the main relay with ignition on. The only
function you'd lose by not supplying this with the ECU's logic is the power to burn off the AMM wire."
After peering at the Bentley thumbnail diagrams (a purely recreational pastime here at Anal Engineering), my beady peepers discerned that with LH 2.4, the following items would (now?) be lost without +12v from Main Relay 87/1:
• Injectors
• AMM 5
• ECU 9
• and the "pick" (old ibm relay term) to the Fuel Relay, terminal 85 (!)
Terminal 87/2 still feeds Fuse 4 and the Main Pump as before, but Fuse 4 now also feeds the O2 sensor heater (in parallel with Tank Pump).
The only reason I picked up on this is because I'd reviewed the '93 940 W.D. (the Regina is essentially the same as 2.4, in this area). So I was vaguely aware (getting to be more and more my usual state) of the 2.4 differences.
To think I'd be checking up on you is, of course, absurd.
Bruce
P.S. Good pictures. Hope I don't have to get to that level (being strictly a 12v relay & wire guy), but am glad to know that you've been there, and are availble as a resource.
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67
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Another smile creeps over my face.
(I was just testing how carefully you read posts)
Actually I had good intentions this time but failed the follow through in my wording. I was thinking of which of the two functions provided by pins 20 and 21 could you easily and safely work around if they failed. As far as I've determined (and the circuitry is all discrete here so quite traceable) the only reason to have a pin 21 is to allow the whole thing to remain on for AMM burnoff; in other words, the main relay is just on and off with ignition otherwise, so, except for the burnoff timer, it wouldn't really need a computer to control it.
But the words came out sounding like I thought that is all the main relay did! In any event, you could safely work around a failure at pin 21 by adding a simple relay that would energize the main relay when the key is on. But pin 21 never fails anyway.
The workaround was brought to mind thinking it might be a fairly safe matter to connect an old k-jet fuel pump relay to sense the ignition pulses from the EZK and provide a ground for the failed pin 20 output. I think that, and some homebrew 555 timer contraptions configured as missing pulse detectors, has been hacked to avoid looking for another ECU. Something I might do on my car, but not try to advise remotely. Imagine some non-hobbyist buying that car...
I'd still like to know who did Rex and Regina. Was it Bendix, Bosch, or the both of them? The compatibilities you mention are surprising if its not Bosch.
Sorry again for the bum steer. I did read that part thinking I could have done better.
--
Art Benstein near Baltimore
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Guys I appreciate all of your help. Time for me to look for a 951, have a great evening!
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Hey Shaggy,
I also have been on the verge of replacing the ECU on the 92 wagon my son drives, due to random no starts. While talking to him tonight he mentioned that the problem seems to correct itself after he has made some kind of physical contact with fuse #6.
I've checked the fuse before and it was clean, the fuse clips have been clean also. But I got a flashlight and took a closer look at the block.
I was surprised to find corrosion were the clips enter the plastic block. It was enough to make me wonder if I'm getting good electrical flow thru the block. As a temp. fix I sprayed it with some elec. contact cleaner I had, but this stuff doesn't cut corrosion.
So I'm going to pull the whole fuse block and see how bad it is. And either clean it or replace it. Has anyone out there found this problem?
You might want to take a close look at the fuse block before you buy that ECU. If this doesn't solve the problem there will be a #951 in my future also.
Good luck,
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Bruce S. near D.C.
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Bruce,
Good find. Fuse #6 is THE primary LH FI fuse. It replaced the 25 Amp blade type fuse (under the hood near the coil) starting in the '91 240, according to the Bentley wiring diagrams anyhow.
Bruce the lucid
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Sold 5/03)
'83 Turbo 245
'76 244 (lasted only 255,000 miles)
73 142 (98K)
'71 144 (track modified--crusher bound)
New 144 from '67 to '78
Used '62 122 from '63 to '67
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N Florida, too bad. Which part number is better than the 561?
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posted by
someone claiming to be VolVolina
on
Sat Jan 10 06:28 CST 2004 [ RELATED]
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Are you in the NYC area? I have an extra ECU you could test with.
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