D12A missing on no load 1550 rpm to 1900 rpm

Hi Pablo, please bear with me here, I'm still getting the hang of this forum. Do you want me to post my email address on here for you or there is another way?

 

Oh man my sides hurt now..... I'm saying the Volvo dealers want drug money to purchase VCAD's and you're saying I can get it as a download with crack............I still haven't stopped chuckling....

 

Hopefully after this post I can pm you - gotta have a minimum of seven posts to do so...

 

Hi Snowwy, I know exactly where you are coming from on this one - you would think there is the requirement to have two operational sensors in order to have the diesel run, especially when you look at the pulse train on a scope for the crank sensor. It has a clear "reset count" pulse ( or in this case a null value point ) which is usually a dead giveaway to be the reference source for every other counter in the engine, seeing as it has accrued error correction every revolution.

Plenty of cars here use the same principle as what you describe.

But Pablo is right - The Volvo literature even describes the function of the crank sensor as performing power balance on idle - and it does it every time the engine comes back to idle - all so you have a nice smooth idle.

 

Hi Pablo,

Thought I might have found something today, but on second thoughts, maybe not.

I decided to check the pedal values in isolation on a multimeter (ie: pedal harness unplugged from loom) so that I could see if the pedal was acting smoothly. On the resistance ranging it seemed quite fine - no sudden jumps in value, no dropouts. Great I thought....now for the idle switch component.

With the pedal at idle position there is no contact - exactly how it should be. When the pedal is depressed there is some pedal movement before the switch actuates - also how it should be. But it is the value that has me thinking - it come up with approx 32 ohms - AHA!! I thought. Found ya!! Most idle switch values are on or off - short cct or open and the presence of a resistive value threw me for a minute. Only a minute though, because I thought it was probably designed that way so that the ecu could differentiate in between a short cct from the the pedal switch and a genuine short cct fault. With the switch value at 30 ohms, the ecu sees that as a bonafide value and is happy, where as if it sees a lower resistance value (read short cct), it would know there is a genuine fault condition present.

My question here is: On just a straight resistance reading, what is the value of an operated switch supposed to be?..... A true short cct value ( 0 ohms ), or is it supposed to be around 30 ohms or something similar.

Regards, L.