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NA car, California emissions. Last couple of months I've been muddling through secondary air system problems. My experience with system errors has historically pointed to the pump itself, and this car had a used one installed many years ago, so I started by pulling the pump, only to find that the motor is good, quiet, and the relay energizes and switches power just fine--on the bench. Further investigation showed that my solenoid valve was NOT working and the valve on the exhaust manifold had a bad diaphragm too. I replaced that with a new unit and got a good, working solenoid check valve. Everything is back together and no more codes, but I haven't heard the motor run in the few weeks since finishing.
Two things I've found on the web:
First, that there is no regular fuse for the motor, but a fusible link--I just don't know where it is and cannot find any info on that. I admit I didn't probe the plug for power TO the relay when I had it out--as the battery was out too.
Second, I've found a couple of posts about the circuit in the ECU that controls the motor developing a fault, only fix is to trace and repair in the ECU or replace the ECU (easy to find).
After doing some other work yesterday, I started the car cold, and it was cold out--about 40 degrees. After a few seconds I could hear and feel pulses in the line to the air pump, so it would seem the porting system is activating. Pump did not run though. Gotta be either signal to the relay or power for the pump? I'd love to find that fusible link and check it, if anyone can point me to it.
Thanks, and season's greetings.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi David,
The fusible link shows in the 97 wiring diagram (TP3917201) pgs 60-61
23/233 Fusible link to 2/53 relay (for 6/54 Secondary Air Pump)
This wiring diagram is only 62 pages and apparently used to show changes
from the 96 Manual (TP3911202)
There are none of the usual pictorals for component locations included with
the wiring schematics in this manual.
Checking the 1996 manual 23/233 is a "Branching Point in the engine compartment"
To/From
1/1:+ Battery (Color Y)
2/53:1A Relay, Secondary air pump (Color BL-R)
Follow these two wires to the Fusable link.
The Pictorals for branching points start at pg 32, I didn't see 23/233
Good Luck, Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks Bill, that's exactly the input (pun intended) I've gotten elsewhere, that the schematics aren't clear on the location. Best I've gotten is that it may be along the route of the positive battery cable. I think I'm going to pull the battery and tray again today and see if there is something evident. It wouldn't make sense that if it's a feed from the battery, it would head back toward the fuse box and then retrace forward to the relay, but one never knows. Volvo has certainly done such things. Hoping to find something "right there" in front.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Look in the 1996 wiring diagram:
Pg 7 shows the relay 2/53 by the drivers side headlight
pg 25 shows the branching point 23/233 looking like its in back of the battery
coming from the fender towards the pos battery terminal
Look for a yellow wire at the Pos battery terminal,not the heavy red wire to the starter. The fusible link might be close to the positive battery terminal,
It could be shrink wrapped to the yellow wire.
If that doesn't work, start at the relay 2/53 and follow the Blue/Red wire.
Why dont you confirm that you have +12V at the relay 2/53 pin 1A (Blue Red wire)
Then the fusible link is good.
The relay could be toast, thats easy to check. get the pinout from the manual.
BB
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Following up: Power circuit is good, and the relay is good. Apparently there is no trigger signal getting to the relay. If I ground it, relay and motor kick in. Sadly, no idea where to go from here, but....the trigger wire is blue white and so is one of the wires on the solenoid valve. That can't be a coincidence, but....Running, after about fifteen seconds, the solenoid valve kicks in because I can hear the exhaust pulse start up in the hose to the blower. Wonder if both the solenoid and relay are grounded by the same lead or pin at the ECU.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi David,
The circuit is in the 1997 wiring diagram page 60
The relay 2/53 pin 1B gets it's switching voltage from the ECU pin 38
It's a Blue -Pink wire You can check this wire for continuity.
Do this first.
You can check/service ECU power and signal grounds:
31/50 power ground
31/51 signal ground
and the engine power and signal grounds
31/32 engine power ground
31/33 engine signal ground
see 1996 manual page 51 (PDF page 127) for pictoral locations
The 97 manual indicates the circuit description for your engine management is:
(SFI) Sequential Fuel Injection, Motronic 4.4 (B5254S)
Look for your exact engine on the Volvo id sticker to confirm the exact engine you have.
I found a discussion of the SAS here:
https://volvo850wagon.wordpress.com/2013/03/08/73-secondary-air-system-fault-vacuum-leak-p0410/
There's some input to the ECU, some sensor to switch the SAS maybe the O2 sensors?
Somewhere there should be a circuit description for the air pump from Volvo.
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Bill, I'm looking at the ECU pinout on line, as I don't have schematics, other than my Haynes (useless for this). So far haven't paid to download factory schematics, but I'm thinkin' about it!
From your message:
"31/50 power ground
31/51 signal ground
and the engine power and signal grounds
31/32 engine power ground
31/33 engine signal ground"
The first two you are referring to are the ECU connections for the grounds, yes?
And the last two are where they go to? On a '95 schematic i found the chassis and engine grounds noted, the last two? One is the ground by the right headlight, the other above the starter. Those didn't change in 96-97 and I'm familiar with them. Other functions are working, so don't think that's the problem.
On the pinout I have four ground notations at the box:
B28, signal ground (check to negative bat term) For switching purposes perhaps, like what I’m looking for?
A28, power ground control module—The ECM’s primary ground perhaps?
A13, power ground Maybe more switching???
A18, Ground (sensor) Common ground for sensors?
DS
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Dont you have the basic Volvo wiring diagrams that I referred to?
The Volvo wiring diagrams are available for each model year for free on the web.
Those numbers TP******* are the wiring diagrams to use, Haynes is generic, and
nearly useless for specific model year cars.
BB
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Hi David,
I found this, maybe this is what you need?
https://www.volvotechinfo.com/index.cfm?event=item.getItem&item=TP2318201
Engine Management System Motronic 4.4(Suppl. to TP2308202) (Design and Function, Fault Tracing, Repair and Maintenance; Gr. 23,28)
Item:TP2318201
Page Count: 276
This manual contains the new features for the 850 (B5254T) from model year 1997 with the Motronic 4.4 engine management system.
Price:$41.50
Maybe you can search the web and find it for free?
Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Honestly I'm not averse to paying that for the manual, if it's complete. We have two '97s, worth it.
I'm annoyed by the $15-20 for the schematics downloads, as the set I purchased did NOT include the injection/emissions diagrams! Basically just the same stuff the old Haynes has, in nicer format.
Thanks for the link!
Dave
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Look at this thread:
https://www.matthewsvolvosite.com/forums/viewtopic.php?t=20348
No air pump unless the engine is cold AND in motion
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks Bill, Yes, have seen a couple of posts about the 10mph issue. I have my doubts about that, but not certain. I'm going to check again this morning, as it's cold out and everything else has been verified, but I haven't heard the pump run under any circumstances at all in over a month, with or without the other repairs. Verified the relay's trigger wire is intact via continuity last night. Thanks for that link. I share your frustration about search engines bringing up "pay for" stuff much more readily than free--our economic system at its finest-LOL! I had found a couple of manuals on the web for sale, but the picture of the one in your link gave me the correct number, and I purchased one off of Ebay last night.
After checking the feeds last night, the only other curiosity I've noticed: My mileage seems to have dropped considerably. I've had the battery disconnected to get to the pump, and I'm only going by the dash display for now, haven't checked it via fill-up calculation. Also, I've only driven back and forth to work and around the neighborhood at low speed, which is poor mileage territory. Wonder if the ECT is bad, but the gauge is reading correctly. Sigh. Will have to check my maintenance log and see when it was last changed. For now, off for a cold-morning trip around the block, see if the pump comes on after.
DS
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Haynes schematics are almost useless, you want factory schematics for your car.
You can try search engines: Google, Startpage, Duckduckgo, Qwant, Bing, etc.
More and more the search engines deliver paid advertisers wanting $34.95
for stuff thats out there for free.
How many search engines aren't the Google mob?
I just had disappointing results from Searching for specific manuals: lately the search engines have amnesia about the free stuff unless you are lucky and have the correct search string. (I suppose this is to protect them from antitrust actions)
You can goto www.startpage.com and search this string:
"volvo 850 wiring diagrams"
Then you start to home in on usefull info.
This is from startpage:
Goto: https://www.yumpu.com/en/document/view/29679775/volvo-850-1997-wiring-diagrams
Try various search engines and compare results, let me know if you find
a better search engine. They tend to disappoint with the monopoly in place.
BB
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks Bill. I'm familiar with that article! One thing I forgot, is this:
"The Motronic 4.4 MFI controls the pump relay and solenoid valve using separate outputs from the engine control module (ECM). "
This jives with the one post I found with the same symptoms I have, solenoid activating, but no pump running, and a bad ECU. I take exception to the part about the system not activating until the car has been driven, as I'm sure I've heard the pumps run on cold mornings with the car just started in the driveway--at least I think. Regardless, it doesn't run even after the car has been at 10 mph. The relay isn't getting a ground signal at all.
Can you suggest a site where I can find a pinout for the ECU? It is 4.4, as it's NA. I want to see if I can trace all the grounds before I buy an ECU.
Thanks for the pin numbers. DS
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Look in the 97 wiring diagram
(Volvo page Nr 21) I think this is yours.
but there's several choices for SFI so confirm your engine #.
The PDF pages dont agree with the Volvo page numbers.
You need your specific engine # Look on the pillar sticker - I'm not sure where you find that info.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Will have to figure out exactly which management system it is first, as you suggest. I thought the turbos were 4.3 and NAs 4.4, but the web is telling me different. Pink/blue, that's right (thought it was blue white).
By "pin out", I meant the actual positions of the connections on the ECU. If it's not the switching via the ECU, it's going to be the ground before the ECU for that circuit. Really a strange thing to happen, losing that feed. Unless a wire broke someplace--hope not.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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The pinout for connectors/ecu etc is in the manual.
You need use the 1996 AND the 1997 which just shows new changes.
Happy New Year, away from crowds.... Bill
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Just finished eliminating my doubts, verified it's 4.4 (261203077 ECU). Gotta go study schematics and pinouts. Spent the morning dealing with coolant leaks. Thanks for the help, and Happy New Year--however quiet.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Not an answer, but a good read:
https://www.matthewsvolvosite.com/forums/viewtopic.php?t=33405
--
Keeping it running is better than buying new
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Thanks Klaus, I had not seen this, and I think I've read about 100 threads on the interwebs. It is the second one in which someone is discussing the ECU as the source of the problem. I have been unable to re-find the other post, in which a poster said he replaced the ECU and the problem was solved. I wanted to dig that one up because it had a lot of his tracing steps in it. Pretty sure it was on a UK site.
I did pull the ECU yesterday and examined things, including pins and base, but it was getting too dark and cold to start tracing. NA ECUs are so cheap, I'm tempted to get another and try it, but of course there's no guarantee it won't have the same problem, so need to make sure all the lines are good first. It's so bizarre that so many things failed at once. Solenoid valve was bad, check valve failed, and the pump stopped running, all within a few weeks.
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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David
The article explains the SAS system.
There's engine vacuum control to the SAS too.
BB
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posted by
someone claiming to be
on
Wed Dec 31 18:00 CST 1969 [ RELATED]
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Confirmed the relay was good when it was on the bench. Plan now is to find the yellow wire first, as you suggest, see what I can see along that route. If nothing immediately visible, then yeah, gotta get back down to the motor and relay, put a temporary power source to the cables, verify power at the relay, then trace backwards from there if not. Since the motor is good, there's no reason the fusible link should have melted, if that's the type it is. Very curious. Will post back later today, and thanks.
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