Hi Don,

See if you get any codes at port 2 and 6.

Clean the CPS connector, look carefully at the Harness pins to see if they are
damaged, or spread open. Use dielctric silicone or Penetrox on reassembly.

I heard from Dave Barton today and here is his take on sensor connectors:

"The only issues with sensor connectors that I can think of can be corrosion
on the contacts, which can be reduced using ACZP. Unless of course the pins
get damaged from abuse, bad removal, etc.
I have those connectors in my harness parts page:
https://www.prancingmoose.com/blackvinyl.html#EFIplugs"

ACZP = Anti Corrosion Zinc Paste = Penterox-A

You can also try disconnecting the battery for a minute to reset the ECUs.
This fixed my sudden no start condition in my 93 940. I wonder if that was a fluke, or if it will help you too.

Try the easy stuff first and see if you get any luck.

Bill

Hi,

"Does oil contamination effect the CPS?"

--> Normally no. Consider a similar example like the vehicle speed sensor (VSS) at rear differential. It works with same principle as the CPS. The VSS is located slightly above differential oil level thus subjected to oil splashes and wear particles (magnetic or not). Yet it still works everytime. Very rarely VSS need to be replaced like the CPS. Mine is still the VSS from factory 24 years ago.

Something to think about,
Amarin

A magnetic field such as the sensor's will go right through, unaffected, any none metal material. Any metal particles will simply conduct the field as well. There would have to be a large amount of metal, such as the size of the sensor itself, and all on one side to distort the field pattern. The weakest part is the wire lead. You may want to provide additional support to it to prevent constant flexing due to vibration. If the ring gear teeth were completely filled in with metal particles that would prevent the necessary fluctuation of the field that is required to generate trigger signals.

In addition to the good advice of others here about CPS operation, good signal and good contact, premature CPS failure can be due to premature failure of the protective cable insulation and foil shielding. Low quality cable construction and a harsh engine operating environment can speed the demise of a cheap CPS. Engine twist and vibration flexes the cable. Volvo uses plastic standoff clips on the water pump return line behind the block both to keep the cable from abrading against the return line and firewall, and just as important to move the cable flex point from the sensor on top of the bell housing (a vertical flex point) to the cable section between the firewall clip and the upper standoff (a horizontal twist flex). If the clips are missing (NLA from Volvo) then you can try fashioning your own using a figure 8 plastic zip tie (UV proof, thick one) through a stub of vinyl or rubber tubing as the standoff.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Don,

I agree with B.B. that you just might have the problem in your hand. You have said you can wiggle it and things change.

As far as I know any oil film doesn’t affect the sensor’s function. It’s not a nice thing to have oil leakage.
The rear main seal is probably the largest seal on the whole car.
The oil gets sloshed about as much backwards as forwards. So there’s a reason in here somewhere?
Crankcase pressure and flutter doesn’t help matters either.

The CPS works by not sensing a series of holes in the flywheel until one solid area (no hole) come by under the sensors gap. This causes a magnetic flux and like wise a change in conductance or really a signal amplification that the ICU needs to see to trigger ON or OFF other electronic components.
One is located behind the battery and a larger flat connector.
This item breaks the power to the ignition coil and causes the spark plugs to fire.

An intermittent no start or miss fire can be, or is, a three step or component operation.

The connection on the ignition coil relay can do the exact same thing and can go in/out intermittently.

It’s very hard to tell which is more at fault.
But if the system relay under the glove box is clicking on to run the pumps and the injector circuit.
THERE is orange wire in the AMM that helps troubleshoot that part.

If it doesn’t have spark jumping a gap from the coil wire to a strut stud in front of the coil then clean the connector on what I call an Igniter/ignition coil relay. It does what the ignition points and a condenser use to do.

Sometimes it has been recorded in Brickboard posts that just unplugging it and putting it back on scrubs the terminals a wee bit.
Inspect for a loose or deep pin and green stuff on all of these connectors.
A small amount of dielectric salve helps to keep the “bugs” from returning.

Also if the heat sink transfer paste on it underside isn’t change every ten years or so, it can lead to heat related malfunctions in the summer.

Isn’t it nice that “Behind a battery” is about the best place to hide something in plain sight.
Having a bad connector, in a hand, is like catching a green gremlin by his short fuzzy hairs.
😵‍💫

Phil

Hi Don,

Why don't you service the connector?

Clean with 90% alcohol and a toothbrush then blow out with air,
Use a little smear of dielectric silicone, or Penetrox.
Maybe you have a buggy connector, and it's easy to find out.

Bill