How To: WUR (Warm Up Regulator) CPR (Control Pressure regulator) rebuild kit

[Helirich]

The heater should not have a connection to the case. Open the cover in the WUR and you will see a wire has burned off the insulation and is touching the case. This is not a rare problem. Mine also had this problem. The wires are Teflon insulated and that insulation is very thin and wears through with vibration if it is touching the case. Move the wires from case if still intact and use some high temp silicone to hold them in place.

I took it apart. Please look at this.

5DD74149-E756-4BFE-A9EC-C1B5B9F810D1.jpg

You can see the two blue wires coming from the plug pins. The top on has two yellow wires off of it. One of them goes to a ring terminal on the bolt. That bolt goes into the case. How would that not be on purpose? Is mine wrong?

Can you verify that both of your pins are open to the case?

Edit, it appears the blue wires are just insulation over yellow wires. But it doesn’t change my ground question.

[Bitsyncmaster]

I took it apart. Please look at this.

5DD74149-E756-4BFE-A9EC-C1B5B9F810D1.jpg

You can see the two blue wires coming from the plug pins. The top on has two yellow wires off of it. One of them goes to a ring terminal on the bolt. That bolt goes into the case. How would that not be on purpose? Is mine wrong?

Can you verify that both of your pins are open to the case?

Edit, it appears the blue wires are just insulation over yellow wires. But it doesn?t change my ground question.

I just did a resistance check on mine and your correct. One pin to the case is zero ohms and the other pin is 18 ohms. I think my original WUR was not connected to the case but the wires were burned so I replace the WUR.

Since your wires look good the connector must be wired correctly.

[Bitsyncmaster]

I looked on an old computer to see if I had a photo of the burnt WUR wiring but could not find anything. I know I posted about it but that was before DMCtalk crashed and lost all the old posts. There may be other owners photos of it since I know about 3 or 4 other owners having that problem.

[nkemp]

......... One pin to the case is zero ohms and the other pin is 18 ohms.

Begs the question why they included a ground wire.

[Bitsyncmaster]

Begs the question why they included a ground wire.

All I can think of is some WUR do not case ground. I've seen photos of units without the thermal switch not ground the case. By the way, does that thermal switch reduce the heater power or increase it when hot?

[nkemp]

All I can think of is some WUR do not case ground. I've seen photos of units without the thermal switch not ground the case. By the way, does that thermal switch reduce the heater power or increase it when hot?

Might the switch turn off the heater circuit when the engine gets warm enough? FWIW, mine is grounded to the case as well.

Seems that the circuit diagram attached above could use an update to incorporate the switch and internal connection to ground.