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Car has been running fine lately, no problems. All of a sudden, check engine light comes on while driving, no noticeable difference on highway/local road. However, the difference is apparent when the car is at a red light or in park idling.
Codes read back are 3-2-1, 2-2-3, 1-2-2, 1-2-1. I have a regina system. These codes correspond to:
3-2-1 Signal missing to/from cold start valve
Source of fault: Radio suppression relay
2-2-3 Signal missing to/from idle valve
Source of fault: IAC Idle air control valve
1-2-1 Signal missing or faulty to/from pressure sensor
Source of fault: MAP Pressure sensor
1-2-2 Signal missing or faulty to/from air temperature sensor
Source of fault: Air temperature sensor
Okay... too many things are supposed to be broken at once. Did something in my wiring just die? Wiring harness? I tried disconnecting and reocnnecting the connectors for each of those sensors. They appear clean and snug, and it's doubtful they all just decided to lose contact simultaneously.
Any suggestions are greatly appreciated, thanks!
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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Very strange. The car's performance seems to be just fine. I am wondering if the IAC is somehow triggering the 1-2-1 bad MAP sensor code. As far as I know, if the MAP sensor is not working, the car doesn't even run.
I disconnected the MAP sensor with the car off and tried to start it, and it doesn't start at all, just keeps cranking. Does anyone know if MAP sensors can go partially bad? When I tested it for functionality the other day, the voltage did go up and down based on the amount of throttle applied, so it would APPEAR to be working.
After resetting the check engine light yet again, the only codes now are 3-2-1 (cold start) and 2-2-3 (bad IAC). Ran it for a minute or two, gunned the engine a bit, and the 1-2-1 code is nowhere in sight. Very strange.
I guess I'll replace the IAC first and see if the other codes stop showing up.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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I reset the codes yet again after having tested the MAP and air temp sensors for functionality. I started the car up and let it run for a minute and shut it off, and pulled the codes again. 2-2-3 (IAC) and 3-2-1 (cold start) and 2-3-3 (IAC valve closed, hrm)
I reset it again and the only ones showing now are 2-2-3 and 3-2-1. So it seems like my IAC is dead, and god only knows why the other codes showed up. I'll drive it on the highway later and pull the codes again tomorrow to see if the MAP and air temp codes pop up again.
Sigh. Nearly $300 for that IAC... I wonder if the Bosch IAC works on a regina system. Anyone know?
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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The IACs look different. The regina only has 2 leads on it. The Bosch apparently (according to the FAQ) has 3. Definitely not interchangeable. So much for that. Guess I'm going to have to replace it.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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After checking your web site(nice job!) to see what you have done and the climate your car has been in: Double check the wiring harness. You may have a break some where. I also doubt that all four things can go bad all at the same time.
With the engine idling, you could unplug each of the offenders, one at a time to see if that changes anything.
BTW, I would opt for new shocks/coils/bushings at all four corners to improve handling, not lowering or stiffer front roll bar. Getting a real tune up at a very good Volvo shop would also help (figure about $300). And buy a floor jack!
Klaus
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98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)
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Thanks for looking through my site. :) And thanks for the suggestions about bettering the performance, but as you can see, I have some other things to worry about first now. =P
By wiring harness, do you mean the harness/connector at the ECU behind the kick panel? I'll triple check it, but it looks okay to me.
I disconnected the IAC and it made no difference in performance (idling very poorly still). I disconnected the air temperature sensor located immediately behind the airbox, it made no difference. I didn't get a chance to disconnect the cold start valve/injector but I doubt that would have made a difference at the moment being that the car is warmed up.
As a desperate measure, I disconnected the battery in the car for a few minutes hoping that it would 'reset' something but alas, no such luck.
I called up FCPGroton for a worst case scenario, in case all of these sensors/parts actually were broken and I needed to replace them all. I've concluded that if all of these parts are indeed broken, I'm going to have to cry because it's way too much money. The guy on the phone has never even heard of a MAP sensor for my year/model or an air temperature sensor, so I would have to buy from the dealer.
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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Unfortunately, these codes could have been stored for a long time. Glad you cleared them out! Which came back? Please don't say all of them! If so, it is a wiring problem. Check the ground near the ECU for rust.
Klaus
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98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)
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They all came back. I don't believe the codes have been sitting there for that long, but if they have, no symptoms manifested themselves until yesterday. The check engine light wasn't on either until yesterday.
The idle is definitely not where it's supposed to be. Very low idle ~500RPM. Also just pulled the kick panel to look at the grounds near the ECU and it looks in order. I disconnected the ECU and looked at the contacts, and they all look good as well.
Argh, this is ridiculous. I wish I had a spare IAC to test things with too, but that wouldn't explain the 3 other codes having nothing to do with the IAC.
edit: Hmm, you might be onto something. Upon reviewing the FAQ again, maybe the check engine light didn't come on until the IAC broke and like you said, the other codes might have been stored in there for a while without triggering the light. Unfortunately, the table in the FAQ for the Regina system doesn't have a * next to the codes that turn on the Check Engine light. But still, oh geez, if that's the case, I have a lot of broken things I need to fix!! :(
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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Wow! When it rains it pours.
I believe there is a maximum number of faults that cam be stored at a time - like about 4. It might be that the OBD would have liked to display more, but couldn't.
The puzzle is to figure out what would be common to all. The ECU, however I don't know if I've ever heard of a Regina (Bendix?) ECU going bad. I'm wondering if the ECU may have all of a sudden developed a bad ground or something. You might want to open the kick panel and see if any moisture has gotten to it. I'm not sure if a bad engine-to-chassis ground would cause errors like you're experiencing, but that also might be a something to checkout.
Good luck.
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I'll check the ECU and the grounds. I thought it might have something to do with that, but I was looking at the FAQ and by most accounts, when an ECU goes bad, bad things happen that would cause the car to not run at all. But I'll check anyway, it'll only take a few minutes.
I did have a leak around that area (water going into the blower motor) but I fixed it up a while ago.
Also, with regards to wanting to show more codes, it only shows 3. I cleared the 3, and then it displayed a 4th, and that was it.
So far, the only symptoms I can see are hard starting after sitting for a while, and poor idle (low RPM... it idles around 500RPM now). I have no idea how the mileage is or anything else.
Any other ideas?
Thanks!
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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This is based on Service Bulletin # 135 from January 1990 (applicable to '89 and '90 740 and 740GL), which says that 3-2-1 may be a false code, due to a circuit modification related to the Cold Start Injector/valve..
As a quick check, peel back the Cold Start connector boot and see if the Blue-Green + wire has been disconnected, taped off, and replaced by another wire (color unknown) directly from the starter solenoid.
If so, you can confirm the modification by checking for continuity from CS pin 2 to starter auxiliary terminal 15a or 16 down on the solenoid. If there is continuity, the RSR is no longer in the CS Injector circuit.
QUOTE: "As a result of this modification . . . Fault code 3-2-1 (cold start injector) will be permanently stored in the self-diagnostic memory. However the Check Engine Light (CEL) will not illuminate."
If I find anything on the other codes in my '93 greenbook, I'll edit this post, or post again.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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Hmm this sounds very familiar to me! I think you're right about this. I'll check tomorrow during the daylight hours.
The other codes are killing me though. Ugh, I hope my IAC isn't broken, because that's a pretty expensive part. Easy to replace by myself, but sooooo expensive.
So far the IAC is the only code that's displaying a symptom. I would think that if the MAP sensor and air temperature sensor were broken I'd be getting problems on the highway... but I'm not.
Thanks a lot!
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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I had a similar problem. Check the ground under the intake manifold. It "plugs" into a connection on the block. Corrosion is a big factor at this connection!
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1965 Mustang A block 4 speed, 1969 Cougar Eliminator, 1990 Super-Charged Thunderbird and a car (740) that my wife can drive!!!
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"Check the ground under the intake manifold. It "plugs" into a connection on the block."
That sounds like what's shown on my '93 940 wiring diagram "locator" page. But I looked at the car and am not sure about it. This ground is appears in the Fault tracing pictorial for the subject codes.
I can find a Brown (correct color) ground at the front fuel rail bolt, but it takes a dive and disappears into a harness bundle, leading down. Same for the Black ground at the rear fuel rail bolt.
Any more specifics to locate the other end of this/these ground leads?
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.
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I will try. Under the intake between Cyls 2 & 3. Look for the freeze plugs. It is a simple two wire plug. Not in the bundle of wires.
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1965 Mustang A block 4 speed, 1969 Cougar Eliminator, 1990 Super-Charged Thunderbird and a car (740) that my wife can drive!!!
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I went out to look for that ground wire but didn't see anything immediately apparent. I saw a few things that looked like they might've been grounds and inspected those. I unscrewed/unplugged and reconnected them just to make sure.
HOWEVER, while I was out there, I took out a multimeter and disconnected the IAC. With the car running (and idling poorly) I checked the voltage across the lead that goes to the IAC (2 prong connector) and there is a constant 12V being supplied to it. I guess my IAC is actually bad??? (Goodbye $$$) :(
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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Per instructions here:
http://www.brickboard.com/FAQ/700-900/EngineSensors.htm#ReginaAirTemperatureSensor
I tested the leads in the rear of the MAP sensor while the car was up and running. I applied throttle which decreased the vacuum pressure on the sensor causing the voltage to rise, which means that the sensor is functioning as far as I can tell.
I removed the air temperature sensor from the car and stuck it in the freezer and warmed it up with a hair dryer (aka heat gun ;)) and the resistance did decrease as it heated up.
This leads me to believe that BOTH of the sensors above ARE indeed functioning.
The cold start valve you already explained and I seem to recall that I did pull that code once a few years ago when I checked for codes and got the same response. And the IAC... well, unfortunately it seems to be broken. Now why in the world is the OBD throwing a code for both of those items when they're obviously working? If both the MAP and air temp sensors were broken, in theory my car shouldn't even be running properly. I would think it'd be like having the MAF disconnected in those cars that have it (limp home mode).
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Ken
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'
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