What's up... so tonight I pull up to the house, and immediately notice something's not right and the cel lights up as well. Hook up the scanner to find 6 error codes, P0508 P2401 P0245 P0445 P0031 P0037. I researched online but couldn't find much, other than the evap code could be a loose / faulty gas cap, bad hose and/or a blown fuse. Don't understand the 02 sensor codes as they are less than 10k miles old. Recently installed a turbo blanket....maybe they don't like extra heat be pushed thru the exhaust? Can't imagine that being the problem,but who knows. As for the waste gate code, recently installed a "bleeder" plug in the vacuum hose going from the TCV valve to the wastegate.... thinking it would slow the wastegate a bit, nothing noticeable on the gauge tho. So that's most likely causing the 245 code. Some say they cleaned the MAF and throttle body and the IAC code went away, others did all that and replaced the IAC and still had the code. What to do.... up until now she ran like a raped ape (148k miles, 3 inch aluminum air intake, 3 inch stainless down pipe and exhaust). Any advise would be greatly appreciated!

 

I'd suggest that if all these codes popped up at the same time, that you're looking at a single failure causing the cascading symptoms. My gut tells me your "bleeder plug" would be the first place to look. I'm thinking it could be causing problems in both the vacuum and exhaust sides. I'd put it back to "normal" and clear the codes and see what happens.

 

Thanks habbyguy! Will do and hopefully that's all it is. I ordered the evap solenoid from fcp euro, as this one has most likely never been replaced. Probably not the issue, but seems to be that these sensors don't live much past 100k miles. Tried starting the car this am, turns over but won't fire up. Not sure when I'll get under the hood, as its been hot and tropical with no end in sight till next Tuesday. See what happens, keep ya posted as to what I find. Thanks again!

 

there may be a correlation to the happy meal of codes and your no start. May not be a bad idea to get it a jump start then measure system voltage. Its quite possible you have a charging issue and when the voltage dropped below the system's threshold, random codes can pop up. You may want to restart, check the charging system/battery then clear the codes and go for a drive to see what reappears.

 

Thanks Moderator, I'll give it a try . Removed bleeder plug to wastegate and installed new evap solenoid this evening..to no avail. Wants to start but won't. What's the life span on the IAC valve?

 

Put the charger on the battery today, cleared codes, still won't run. Could a bad IAC valve be the cause? I'll hook the ohm meter to it see what that says. Maybe the fuel pump?

 

Ok, so I discovered the problem...no power going to IAC valve. Checked the fuse's and the engine sensors fuse was blown! But why? Possibly my wastegate bleeder? Any one have any suggestions or experience with this? So now I wait for the IAC gasket....

 

Which fuse was blown (not sure what the "engine sensors fuse" is)?

 

That's how its labeled in the fuse box..."engine sensors"

 

Interesting... I only have a 2004+ manual (having a 2005 V50) so can't really tell you what that fuse protects. I'd recommend finding an online electrical manual for your version of S40 and see what's powered through that fuse. Then it's "just" a matter of figuring out which of the suspects is guilty. If it's a circuit that doesn't normally have a lot of current draw (and I'd guess that's the case on a circuit that's labeled "sensors") you might be able to use a leaded light bulb in place of the fuse. A dead short will just light up the light bulb instead of blowing another fuse, so you can start unplugging things until the light bulb goes out. OTOH, if that circuit also supplies heater current to the O2 sensors, you'll have trouble using this method (since they draw so much current that the bulb will light up nearly full brightness unless you use something bigger like a headlight bulb). Or, you can pull the fuse and put an ohmmeter between ground and the LOAD side of the (missing) fuse. Don't connect the ohmmeter to the SUPPLY side, as the 12 volts from the battery will have you wondering about the smoke pouring out of your meter. ;-)

FWIW, if the fuse is a 10 amp fuse, figure that the resistance should be over 1.4 ohms (under that, and the circuit will draw more than 10 amps at the typical 14 volt "running mode"). If it's a 20 amp circuit, the resistance should be over 0.7 ohms. Of course, its important to know if your meter leads / connections have any resistance themselves, to factor in since you're dealing with such low numbers. But hook up the meter, and if you get resistances below those points, start unplugging things until the resistance goes (probably well) under the "goal".

 

Thanks habbyguy, really appreciate your advice. I'll do some detective work with the meter and see what I can find..it is a 10 amp fuse.

 

Ok, finally got the IAC gasket. Got it back together, put new "engine sensors" fuse in,turn key on and still no power to the IAC!! WTF! Didn't blow the fuse tho. Fuse blows when cranking the engine. Checked the exposed wiring to the IAC and it looks good up to where its spliced in to other wires. Started checking all sensors I could with the ohm meter which appear to be ok...was getting reading on meter not sure if it was with in spec., so that would at least rule out any shorts. The one that didn't give a reading, is the second plug in from the post cat 02 sensor (on top of firewall where the 02 sensors plug into ) Started pulling that wire to see where it goes, but it quickly got buried in other wires. So at this point I had enough for one day...tried researching online to figure out what it is, but couldn't find anything... not even a wiring diagram. What can it be?

 

Appears to be the knock sensor. Don't think that this would be blowing the fuse.

 

I wouldn't rule out anything at this point. If I had a wiring diagram for your car, I could tell whether or not the knock sensor is connected in a way that would make it a candidate for blowing the fuse (that is, wired directly to battery voltage through the fuse). Interesting it blows only when you're cranking the car - are you sure you tried the ignition switch in position II (run position) prior to cranking?

It really would be helpful to have a wiring diagram for your car. Sadly, that's just not how Volvo does things... it used to take me just seconds to research something on my Acura with the .pdf manual, but Volvo's VIDA-based "manual" is so convoluted (at least the way I had to install it...) to be totally worthless unless I'm sitting in my car actually diagnosing a problem. You might be able to find a manual online - I did find an electrical manual for my car ('05 V50) online.

 

Yeah, ignition was definitely in the run position. Do you remember the name of the website that you got your electrical manual?

 

Sorry, no... I really don't recall where I got the manual.

 

Okay, so here's the latest...pulled every sensor connection I could find (crank, cam, maf, iac, map, knock, both 02's) one at a time, crank the engine, blowing the sensors fuse with every try! Pulled the ignition & fuel injector connections with the same result. Went thru 14 fuses in the process!! The only thing left to try are the big connectors behind the air intake box, but ran out of fuses. So it'll have to wait for another time. It just doesn't make sense, what could possibly be blowing the fuse...especially after unplugging all sensors/connections possible??!! Just don't get it...it was running great, then out of the blue starts idling rough, shut it off and hasn't run since.

 

Here's an old sparky trick that can save you a lot of fuses (or ammeters)...

Get a high-wattage light bulb with leads, and plug it in in place of the fuse. That way a dead short on the circuit will just light up the light bulb. Even better, you can just root around moving, unplugging and wiggling things until the light goes out, and you've found the problem. Might be easier if you crimp "fuse style" connectors on the end, or maybe just add some longer wires so you can put the light bulb where you can see it when you're troubleshooting.

Barring that, you can also just put an ohmmeter (measures resistance) on the LOAD SIDE of the (removed) fuse. Don't hook it up to the SUPPLY (battery) side or you'll smoke it. But then you can just use the ohmmeter as an indication of how much power that circuit would be drawing. For a 10 amp circuit drawing maximum power (10 amps), figure that the circuit should be around 1.4 ohms (14 volts divided by 10 amps gives you the resistance). For a 20 amp circuit, the max would be a resistance of 0.7 ohms. Lower resistance than those numbers means you're gonna blow a fuse every time. Again, just hook up the meter, black to ground and red to the LOAD side of the missing fuse, and start pulling things until the resistance goes ABOVE those values (it should be pretty obvious).

You can get a multimeter for chump change these days, or even free from Harbor Freight if you've got the right coupon. They aren't lab-grade, but will generally be good enough to use for this kind of troubleshooting.

 

Thanks, only trouble is fuse only blows when cranking the engine...

 

Think I found the culprit...appears to be a short in the crank shaft sensor harness. So now the fun part, tying to find it!