1994 850 manual Code 2-1-4 Port A6

Post by **shaker_chi** » 12 Sep 2014, 04:03

I installed a new alternator about 6 months ago, and since my tachometer has been working erratically. I'm not sure if I stretched a wire, etc. Today, I was pulling codes and found a 2-1-4 in port A6 (I have the OBD I system) which indicates "RPM signal absent intermittently". Does anyone know where the RPM signal comes from? The crankshaft position sensor or the ignition coil? I've read some previous posts, but all are with vehicles with automatic transmissions. Any help would be greatly appreciated. I don't want this to turn into a "no start" situation.

Post by **Ozark Lee** » 12 Sep 2014, 07:36

It comes from the crank position sensor. A common problem that leads to that code is the sensor wire looping up next to the coil wire. In its natural state that is exactly where it wants to go.

Volvo actually had a TSB on the subject and the cure was to use a zip tie to fold the sensor wires (both camshaft and crankshaft) neatly away from the ignition wires.

...Lee

Post by **shaker_chi** » 12 Sep 2014, 08:01

Thanks Lee. I'll check it out and zip tie it away from the plug wires.