Camshaft position sensor.

Toplights · Post by **Toplights** » 28 Aug 2010, 08:01

Hi all,Can someone please tell me if a failed Camshaft sensor will allways throw a fault?I have a no start problem on my,
1998 V70 2.5Lt 20V Auto none turbo.I have checked the Crankshaft Sensor and its reading 280 ohms so i am assuming thats ok.
Hope you can help,it will be much appreciated.Many thanks Malcolm.
P/S I have Ilexa Volvo FCR. I use for diognostics.

Post by **jblackburn** » 28 Aug 2010, 09:22

No, not always...they can fail without warning or codes.

That resistance reading is good for the crankshaft sensor, so it's safe to assume it is ok for now.

Toplights · Post by **Toplights** » 28 Aug 2010, 10:11

jabblackburn,Thanks for you'r prompt reply,will do the full camshaft sensor tests on Monday and let you know how it goes,not allowed to play with cars on Sunday,family time.
Reguards Malcolm.

Toplights · Post by **Toplights** » 30 Aug 2010, 08:01

Hi to all,jabblackburn,Just compleated some of the tests as per CPSC page143318.I dont know if its me getting/missreading this information or not,but it seems conflicting to me.Following sections read.

Checking Signal Cable
Ignition on,meter on lead 2 Blue/yellow (to ECM) to ground, should read battery voltage (which it does 11.6V) this seems to be as it should.It then goes on to read,Proceed to test step below, which reads
Checking Signal Cable to ground
Ignition on,connect a test light to lead 2 Blue/yellow (to ECM) to ground,does it light up (which it does)it then goes on to say check cable between terminal 2 plug end and A21 ECM end for a short circuit to ground.
These two readings seem to conflict with each other,am i right, or just missreading the testing instructions?
If i am wrong do the two above tests confirm i have a short circuit in wire 2 Blue/yellow wire between the plug and ECM?
Reguards Malcolm.

Post by **jblackburn** » 30 Aug 2010, 12:41

If it lights up, you've got a complete circuit. If you were to touch one end at the ECM and one end at the end of Pin 2, and the bulb lit up, that would indicate a short circuit.

Unfortunately, there is no real way to test the camshaft sensor itself, but it sounds like your wiring is indeed working as it should.

Toplights · Post by **Toplights** » 31 Aug 2010, 04:15

Hi jabblackburn,great, thats that test sorted and prooved good then.I have read that if you re- connect up the plug to the sensor,then probe no 2 Blue/yellow and no 1 Brown/black,attatch an annolog meter (one with a needle),then spin the engine you should see the needle flcker, (and showing possibly 5V),there is some contention as to weather this figure of 5V is correct.
On Checking the engine control Module connector.
On checking, this reading should show a reading of 0.5 to 3.0 ohms.
Mine measures, (on the meter set on 200 Koms), 5.4 Kohms.
On reflection this seems too high,i would welcolm you'r comment on it.
Reguards Malcolm.

Toplights · Post by **Toplights** » 31 Aug 2010, 13:01

Hi jabblackburn,See my earlier post first please.Today i retested my figures and i may have tested the Checking Signal cable to Ground, wrongly.In the test proceedure it askes if the resistance is infinate and it isent.I get a reading of 1.43 Kohms with my multimeter set on the 20K setting.Does this mean i have an earthing fault in the Camshaft position sensor circuit? your comments would be apreciated. Reguards Malcolm.

Post by **jblackburn** » 31 Aug 2010, 21:52

Maybe...I would crack open the ECU box and try to clean the connections. An infinite resistance sounds kind of odd to me, though for a sensor, but I'm just going off what I'm thinking. Electrical problems/circuits are the most annoying to track down.

then spin the engine you should see the needle flicker, (and showing possibly 5V),there is some contention as to weather this figure of 5V is correct.

Did you get this to happen? 5V should be correct.

Toplights · Post by **Toplights** » 01 Sep 2010, 02:47

Hi jabblackburn,I can borrow an annolog meter (from my lad) later on in the week,i will try the idea out and let you know the outcome,its handy to know it should show 5V.I have been down the route of having the ECU refurbed,i allso have another identical ECU that i use,i duplicate the tests with both and get the same (approx) results from both.

Post by **jblackburn** » 01 Sep 2010, 07:04

You should be able to get that reading even with a digital one - I doubt it changes fast enough that it won't ramp up and down.

I think at this point, the ECU's perfectly fine, and it's a fair bet the sensor's dead.