2000 V70 N/A P1671 Code

dos_volvos · Post by **dos_volvos** » 05 Oct 2012, 00:31

2000 V70 N/A 144,220 miles. P1671 Volvo CMP Actuator Performance Problem Or Signal Out Of Range. While in the process of changing the spark plugs on my nephew's V70 I noticed that one of the wires to the camshaft position sensor(cmp) was crushed. The outside insulation was nicked and the conductor was crushed and exposed - looks like the wire got caught between the black cover and the head. Continued on with the spark plug(NGK Iridium) change. Started up the car - smooth idle - approx. 900 rpms and then the check engine light came on. Prior to the spark plug change there was no CEL. Hooked up the code reader - P1671 Volvo CMP Actuator Performance Problem Or Signal Out Of Range. I took the car out for a test ride. She ran great - smooth acceleration and full power. I figured that the crushed/exposed wire was the cause of the code. Cut the wire at the aforementioned location - solder and shrink wrap. Same code again. I did a search on this great site and read numerous posts on P1671. I did the following:
-cleaned the CMP ports and cleaned contacts with CRC electronic cleaner
-checked resistance at cmp and harness - w/i specs
-checked for voltage to the cmp - no voltage
So where do I go from here? The two cmp wires are buried in a loom that I think go to the ECU. Need some help please..

Also, is there a problem with driving the car with in this condition? It runs great. The CEL remains on - I gave the car back to my nephew to drive. I told him to ignore the CEL for a few days until I get some help. Thanks...

Post by **precopster** » 05 Oct 2012, 17:10

Forget the cam sensor. You have VVT on the inlet cam. This code is a ECM-6400 or camshaft reset valve problem, not a cam sensor problem.

Under the first engine cover you'll find a solenoid. Check the connector to this and the resistance of the solenoid when out of circuit.

Vida/Dice can perform a function test of the solenoid while somebody views it for movement.

dos_volvos · Post by **dos_volvos** » 05 Oct 2012, 21:18

Thank you precopster for your reply. I believe that I was not clear in my description of the problem with my post regarding the cmp. I meant that I checked the solenoid and harness for resistance/voltage. Sorry for my poor description. Right now it seems that the solenoid is not receiving any voltage. I thought this was the result of the crushed wire. Both the solenoid and harness have checked out within specs for resistance while out of circuit. Backprobed the harness while connected to the solenoid - both with key in position ll and at idle. Result - zero voltage. What's my next plan for diagnosing this problem?

Post by **precopster** » 05 Oct 2012, 21:55

Well that IS an unusual one. If you have your radio code I would try a battery cable pull, leave ignition on and press the brake pedal to discharge any residual charge in the system. Then reconnect and see if the ECU starts to send voltage to the harness. All settings will be back to baseline and the ECU will readapt.

As I'm unaware of exactly at what rev range this solenoid is activated, it's hard to say WHEN to expect voltage at the solenoid.

Get back to the forum with your findings and we'll see if anyone else has some experience with this

dos_volvos · Post by **dos_volvos** » 06 Oct 2012, 12:21

Thanks again precopster.I will do the battery disconnect and post the results. Is it ok to drive the car under these circumstances? I going to try to find a schematic somewhere.

Post by **Ozark Lee** » 06 Oct 2012, 13:45

We have the schematics here. There is a tab for them under the repair database tab at the top of the page. They were scanned and there are some missing pages and the pages are not numbered sequentially so it takes some time to find what you are looking for. For backup download the 1999 schematics as well, they are the same but between the two sets they should be fairly complete.

My rough understanding of the valve is that it gets a pulse modulated signal to control it. I don't know if the ECU supplies the positive voltage or if it just varies the pulse width to ground with the positive voltage coming from another source - my WAG is that it is the latter.

...Lee

FASTR1 · Post by **FASTR1** » 06 Oct 2012, 19:07

based on what i read the car supplies 12v on the green orange wire then the pcm pulse width modulates the return wire at 250 mhz , i did verify on my s70 that there is 12v on the supply lead and almost the same on the return leg

dos_volvos · Post by **dos_volvos** » 08 Oct 2012, 09:49

Thank you ozark lee and fastr1 for your replies. My nephew is bringing the car today so that I can check things out. Will post back with findings. Still, is it ok to drive the car in this condition?