98 v70 NA P0455 - my most loyal friend

[abscate]

No on the fuel pump relay causing problems.

Can you post the diagram you found for reference ( we have an agreement with Volvo that users can post them but mods do not)

[98v70dad]

I found one here for a 98 V70 GLT - my car isn't a GLT but maybe it has a similar wiring diagram. This is a 20 page file so I just provided a link. This looks like a scan from a Volvo manual.

http://www.justanswer.com/volvo/2rimx-1 ... -when.html

[abscate]

Yep the GN (Green Orange?) wire should have 12 VDC when the key is on. The ECU opens the purge valve by grounding it on the Blue Green.

Resistance measurement on BG wire won't be too useful

Voltage the on the GN should be 12 VDC to ground

Voltage across connector not useful - no one knows what load the ECU puts onto the wire in OFF state.

[98v70dad]

Yep the GN (Green Orange?) wire should have 12 VDC when the key is on. The ECU opens the purge valve by grounding it on the Blue Green.

Resistance measurement on BG wire won't be too useful

Voltage the on the GN should be 12 VDC to ground

Voltage across connector not useful - no one knows what load the ECU puts onto the wire in OFF state.

I'll check that when I get home if its not raining on me. Note that the first thing in the circuit on the power side is the fuel pump relay. Is it possible that my failing fuel pump relay somehow killed the purge valve? Wiring is something on a car that I've always tried to avoid, but I basically understand the concepts. Trying to find and isolate a problem is another matter altogether though ....I'm not at all good at that.

[abscate]

Very unlikely - you don't get surges and stuff like that in automotive wiring - they just break. Home wiring is different

[98v70dad]

Very unlikely - you don't get surges and stuff like that in automotive wiring - they just break. Home wiring is different

Is there a good way to check the purge valve itself? I haven't suspected it because it is less than 6 months old and its an OEM part from the dealer, but new parts fail sometimes too. I'm thinking that I need to confirm that its a good part.

[sleddriver]

So even though there are a couple of rubber items on top of the fuel tank that haven't been replaced I believe that the likelihood of them being bad is low. Building the smoker will be a pretty easy way to confirm that. The fuel pressure sensor could be bad but I know no way to troubleshoot that.

I had a chance to examine a fuel tank from a 98 off-the-car. Compared to an earlier 850, all the vac pipes on the 98 were HARD plastic instead of rubber. Also since I didn't see nor smell smoke from mine when smoked, I ruled out dropping the tank.

Fuel pressure sensor or Tank pressure sensor? Perhaps you meant the later? I knew mine was OK as I could see the readings change during the diagnostic testing.

Ease your pain & do yourself a favor...build a simple smoker next.

[abscate]

Very unlikely - you don't get surges and stuff like that in automotive wiring - they just break. Home wiring is different

Is there a good way to check the purge valve itself? I haven't suspected it because it is less than 6 months old and its an OEM part from the dealer, but new parts fail sometimes too. I'm thinking that I need to confirm that its a good part.

I measured resistance on one and posted it in a thread. I think all my threads are cross referenced in my 1999 v70't5 Baltic blue maintenance log thread....I had internet on the way to shanghai and was bored.....

On edit...found clip

CEL On, 149799 miles

P0442 Purge fault has been recurring
P0327 Knock sensor signal too low, shows up once in a while

Tested Purge Valve (later model) Resistance is 24.1 Ohms
Specification per AllData is Pulse ratio controlled valve. Resistance 29.7 ±1.4

Replaced Purge Valve, erased codes

Adjust parking brake
viewtopic.php?f=1&t=59241&p=301094&hilit=1999+v70+t5#p301094

Replaced MAP sensor on ETB
viewtopic.php?f=1&t=59647&p=303447&hilit=1999+v70+t5#p303

[98v70dad]

Very unlikely - you don't get surges and stuff like that in automotive wiring - they just break. Home wiring is different

Is there a good way to check the purge valve itself? I haven't suspected it because it is less than 6 months old and its an OEM part from the dealer, but new parts fail sometimes too. I'm thinking that I need to confirm that its a good part.

I measured resistance on one and posted it in a thread. I think all my threads are cross referenced in my 1999 v70't5 Baltic blue maintenance log thread....I had internet on the way to shanghai and was bored.....

On edit...found clip

CEL On, 149799 miles

P0442 Purge fault has been recurring
P0327 Knock sensor signal too low, shows up once in a while

Tested Purge Valve (later model) Resistance is 24.1 Ohms
Specification per AllData is Pulse ratio controlled valve. Resistance 29.7 ±1.4

Replaced Purge Valve, erased codes

Adjust parking brake
viewtopic.php?f=1&t=59241&p=301094&hilit=1999+v70+t5#p301094

Replaced MAP sensor on ETB
viewtopic.php?f=1&t=59647&p=303447&hilit=1999+v70+t5#p303

I measured the resistance of my purge valve and it was about 15% off of what it should be but I didn't pay much attention to that because it's a pretty crude test and the posted "correct" resistance didn't have a corresponding part number. I don't remember if I got the resistance from one of your posts or from somewhere else.

I think a good test for the purge valve would be to put 12v DC on it and see if it actuates.

[abscate]

Yeah, my Dara is for a 1999 which is different valve. I think the 12vdc test and seeing if you can blow through it when applied, and not when removed, is a fair test.

15 percent difference probably isn't meaningful, especially if we aren't sure of part number. I might have another purge valve for a 1998 I my stash though, to test, will check.