Correct way to disconnect CHT/ref/speed sensors?

[RLJett]

Hello all,

I need to disconnect the subject sensors in the engine bay of a 3.2 engine to perform some troubleshooting but have not found the right way to release the connectors. All of the posts I’ve read don’t seem to talk about a specific area to squeeze or if that small metal band needs to be removed first. I’m sure I’m overlooking something obvious but with their age I’m worried about cracking the DME side plug and creating a bigger problem for myself.

[timmy2]

Use a small screwdriver blade inserted in the slots on each side one at a time to pry out the spring and pull back a bit so it stays out. Then connector will slide off.
Caution, the springs will fly out of the garage given the opportunity.

[RLJett]

So the spring is to be removed from the connector?

I’ll lay a plastic sheet under the connectors to hopefully catch those spring. Thanks for the heads up.

[autojack]

There can be a Philips screw holding that spring plate in. I learned that after spending 30 minutes trying to just pull it out. No one had mentioned it and it isn't noted in the Bentley. 1988 car.

[autojack]

Oh, and I'm not sure what timmy2 is describing, but on my car there is a metal plate that locks the three connections together. I had to remove that Phillips screw, then pull that plate towards me to remove it. After that the connections separated easily.

[RLJett]

You are correct autojack, there is that plate with some screws, but I’m not at that step yet. I’ll have to do that to remove the sensor plug eventually. For now I could not disconnect the sensor at the plate you refer to. But thanks for pitching in.

I’m having an intermittent engine cut out issue and wanted to try swapping my ref and speed sensors since they are the same sensors. Kind of like an installed spare. My car starts no problem but every now and then the engine will cut off for a moment. I’ve read all the articles about CHT, speed sensor, dme relay, dme, ignition switch, etc. but since intermittent not possible to perform resistance readings after the fact. So wanted to rule out my speed sensor first.

[timmy2]

I was describing Removal of the 2 and 3 terminal connectors thin Spring lock wire to disconnect.
Doesn't need to come off completely, just not fully seated on the short side.

[john walker's workshop]

Most of the time you can just grab the plastic part and rock side to side as you're pulling and it comes right off.

[A horse with no name]

Originally Posted by RLJett

You are correct autojack, there is that plate with some screws, but I’m not at that step yet. I’ll have to do that to remove the sensor plug eventually. For now I could not disconnect the sensor at the plate you refer to. But thanks for pitching in.

I’m having an intermittent engine cut out issue and wanted to try swapping my ref and speed sensors since they are the same sensors. Kind of like an installed spare. My car starts no problem but every now and then the engine will cut off for a moment. I’ve read all the articles about CHT, speed sensor, dme relay, dme, ignition switch, etc. but since intermittent not possible to perform resistance readings after the fact. So wanted to rule out my speed sensor first.

Hi...Don't bother switching them on the bell housing...Just switch the wires on the metal bracket located on the left side of your engine. There are three wires on the bracket... Two of them are for your speed and reference sensors. They have a number sequence taped on them. If you can't see the number on them under the car, then get someone to watch up above as you move one of them back and forth...

This way is 'easy-peasy'

[steely]

Originally Posted by A horse with no name

Hi...Don't bother switching them on the bell housing...Just switch the wires on the metal bracket located on the left side of your engine.

Swapping the connector alone will not accomplish the test that the OP is attempting.
That said, you need 2 good units to start and run the car, so I suggest that the test might not be a good idea beyond theory anyway.

Honestly, I would just recommend buying new ones (BMW parts are compatible and cost less the last time I looked).

If yours are original, the insulation will crumble off of the wires before your eyes as you remove (or swap) them, so if they were dicey before the test, your intermittent may become permanent.

To convince yourself, stick a meter on them and move the cable - a moving reading is bad.

those puppies are old (like me) - but let us know how you do.

[A horse with no name]

Oops!.. I should have read his question better...He’s at the bracket that I was referring to...Sorry about that...I changed them on our Carrera for preventived maintenance due to their age.

Yes, the BMW ones are certainly the way to go - They were only a couple of inches longer and a whole lot less expensive than the ones for a 3.2

[RLJett]

Originally Posted by A horse with no name

Hi...Don't bother switching them on the bell housing...Just switch the wires on the metal bracket located on the left side of your engine. There are three wires on the bracket... Two of them are for your speed and reference sensors. They have a number sequence taped on them. If you can't see the number on them under the car, then get someone to watch up above as you move one of them back and forth...

This way is 'easy-peasy'

While the two sensors are the same part number I thought they were looking at different parts of the flywheel and therefore I would need to swap there location below in addition to swapping the connections at the DME? My intent it to use the current ref sensor as the speed sensor and the current speed sensor as the ref sensor just to see if my intermittent engine cutout goes away.

[steely]

correct

but I would just replace them with new