What voltage should I be reading at WUR plug?

[jwakil]

Today I was testing my WUR and wanted to make sure the heating element was working. I measure resistance of ~25 ohms across the WUR pins, but when I measure the voltage across the plug that connects to it, it basically read zero. Is it supposed to be 12V? I measured with car off and on, both times it was zero. The engine was hot though. Does the power not flow to the heater if engine is hot, or do I have some wiring problems?

[john walker's workshop]

it get voltage from the fuel pump relay, when the pump runs. reach around and unplug the sensor plate switch plug so the pump runs with the key on. gets battery voltage and ground. same circuit as the air regulator.

[jwakil]

So as long as pump is running it should have voltage, regardless of engine temp? I think I know the answer but want to make sure. I also see the WUR is also connected to the O2 sensor for newer SC cars. Since my engine doesn't use O2 sensor, I wonder if that is why I'm not getting power to the WUR. Anyway, I'm surprised my car runs as well as it does without the heat element. In fact, I've been having problems with too high cold control pressure, which is opposite of what I would expect if the heating element wasn't heating. I think my recent adjustments to the WUR pin has compensated some for the lack of heating.

So....to fix this problem: I read in the manual that the power lead of the WUR should go to pin 30 of the fuel pump relay. My ground brown wire looks ok but I'm reading nothing on the red/white pwr wire. Would I have to run a separate wire all the way to the relay or can I tap into it somewhere in the engine bay?

[john walker's workshop]

voltage is not temp related. tap into a "power w/key on" wire or terminal if necessary. you might want to see if the red/white wires match up in the 14 pin engine loom connector. may just need to swap a wire or two.

[boyt911sc]

Originally Posted by jwakil

Today I was testing my WUR and wanted to make sure the heating element was working. I measure resistance of ~25 ohms across the WUR pins, but when I measure the voltage across the plug that connects to it, it basically read zero. Is it supposed to be 12V? I measured with car off and on, both times it was zero. The engine was hot though. Does the power not flow to the heater if engine is hot, or do I have some wiring problems?

jwakil,

If I remember correctly, you mentioned before in your other post that the FP runs when ignition switch is turned to RUN (not start). If this is the case, the AFS (air flow switch) could be disconnected or bad. Or the FP is hot wired to get power @ RUN.

Check pin #10 red/white wire @ (14-pin connector) in the engine bay. This is where the FP, WUR, AAR, TV are all connected. All these, share a common terminal @ #30 (fuel pump relay).

Once the FP is running, the red/white wire @ 10 (14-pin connector) should have power too. So thus with the WUR, AAR, and TV (thermovalve for some SC's). In summary: When FP runs, the following are all energized (WUR, AAV & TV). Keep us posted.

Tony

[jwakil]

Very good memory boyt911sc. Yes, I checked pin 10 and it is getting voltage when I turn to RUN. (So I guess I have something wrong between the pin and my WUR connector). I will also check the AAR. So does the fact that I'm getting voltage in pin 10 give any info on why my pump runs in the run position?

I'm debating if I want to change anything since the car runs pretty well. I think my WUR adjustment has compensated for the heating element not working. Although if I got the WUR heating working I could probably lower the cold pressure a little more without causing the surging during the warming stage, because there would be less lag between engine temps and WUR temp.

[prebordao]

the heating element effect is just for the first few minutes. afterwards, engine heat "takes over" and the heating element switches off (i think)

[jwakil]

Originally Posted by prebordao

the heating element effect is just for the first few minutes. afterwards, engine heat "takes over" and the heating element switches off (i think)

My understanding is the heating is on all the time (power always applied), but after the engine is hot it's really not needed and just overkill.

[john walker's workshop]

that's the trouble with forums. you get 40 different answers for each question.

[boyt911sc]

Originally Posted by prebordao

the heating element effect is just for the first few minutes. afterwards, engine heat "takes over" and the heating element switches off (i think)

prebordao,

What made you think the heating element in the WUR turns off when the engine gets warm?????? There is no such device incorporated in the WUR that will do this switching off!!!! The heater is ON all the time as long as the FP is getting power from terminal #30 (FP relay). HTH.

Tony

[boyt911sc]

Originally Posted by jwakil

Very good memory boyt911sc. Yes, I checked pin 10 and it is getting voltage when I turn to RUN. (So I guess I have something wrong between the pin and my WUR connector). I will also check the AAR. So does the fact that I'm getting voltage in pin 10 give any info on why my pump runs in the run position?

I'm debating if I want to change anything since the car runs pretty well. I think my WUR adjustment has compensated for the heating element not working. Although if I got the WUR heating working I could probably lower the cold pressure a little more without causing the surging during the warming stage, because there would be less lag between engine temps and WUR temp.

jwakil,

You got to be kidding!!! I couldn't even remember my passwords without writing and saving them in a notepad. The information that I presented to you are all written and documented in the wiring schematics or diagrams in the Bentley, Haynes, and other reference manuals available in the market today. It just so happened that I have a few SC engines to tinker and play around.

Going back to your question, you are doing too much guesses in your work instead of analyzing what causes the problem/s. There is nothing wrong between the #10 pin and WUR's connector. The problem is coming from the fuel pump relay and AFS (air flow switch).

JW has given this advise to you before if I remember correctly. He said to check it. Did you do it? And if I could give you an advise, start reading the Bentley or factory shop manuals and get the right tools for the job. I mean stop working on the control fuel pressure if you don't have a fuel pressure gauge to use. Without it, you are simply guessing!!!! CIS troubleshooting is easy and simple once you reduce or eliminate the quesswork.

Tony

[jwakil]

Obviously there is something wrong between pin 10 and my WUR's connector since I read voltage at the pin and none at the connector. I was focusing on solving the WUR heating problem (as you suggest, eliminate one problem at a time). The fuel pump starting thing is a separate issue. Will worry about that later (As I understand, the AFS switch is just for safety in case of an accident, right?. If so, I would rather just have it end there than have to watch my crushed car get put on a flat bed ).

[boyt911sc]

Originally Posted by jwakil

Obviously there is something wrong between pin 10 and my WUR's connector since I read voltage at the pin and none at the connector. I was focusing on solving the WUR heating problem (as you suggest, eliminate one problem at a time). The fuel pump starting thing is a separate issue. Will worry about that later (As I understand, the AFS switch is just for safety in case of an accident, right?. If so, I would rather just have it end there than have to watch my crushed car get put on a flat bed ).

jwakil,

This is how I would do the electrical troubleshooting in your case:
1). With the IS (ignition switch) @ ON/RUN position (not start) test pin #10 for power using a simple test light.
2). Plug or connect the socket type connector (#10) from the engine side harness. You could do it in many different ways: a). Use a 6" long wire jumper between pin #10 and socket #10. or b). Remove the #10 socket from the connector assembly. Be carefull not to dislodge the other sockets.
3). With the socket plugged directly or with a suitable wire jumper to the pin, test for power at the 'socket' side. And continue up to the other side of the harness for the WUR. It will tell you where the trouble starts.

It could be poor contact or an open line for #10 (red/white). This should be a very simple task for you to achieve. And to determine the FP's problem would be the same technique as above but a lot simplier. Detail later if you're interested. Keep us posted.

Tony

[jwakil]

OK, connector problem solved. Yes. the female position 10 pin wasn't making contact to the male part, was pushed out. Good thing I checked that because I was ready to cut the connector at the WUR to check that. Now, back to the pressure fine-tuning..should be much easier now...

[jwakil]

Damn it!...when I did another check, I got battery voltage at both pins of the WUR connector. What the heck is going on.? If I check voltage between one pin of the WUR connector and ground I should get 12V and zero on the other, right?

[boyt911sc]

Originally Posted by jwakil

So as long as pump is running it should have voltage, regardless of engine temp? I think I know the answer but want to make sure. I also see the WUR is also connected to the O2 sensor for newer SC cars. Since my engine doesn't use O2 sensor, I wonder if that is why I'm not getting power to the WUR. Anyway, I'm surprised my car runs as well as it does without the heat element. In fact, I've been having problems with too high cold control pressure, which is opposite of what I would expect if the heating element wasn't heating. I think my recent adjustments to the WUR pin has compensated some for the lack of heating.

So....to fix this problem: I read in the manual that the power lead of the WUR should go to pin 30 of the fuel pump relay. My ground brown wire looks ok but I'm reading nothing on the red/white pwr wire. Would I have to run a separate wire all the way to the relay or can I tap into it somewhere in the engine bay?

jwakil,

It looks like you've been looking at the wiring diagrams but has not been able to interpret it correctly. The FP, WUR, AAR, and FV relay share a common power input source @ 30 (FP relay). Each of these CIS components work independtly from each other and do not effect each other.

For better analogy, I'll give an example of the above circuitry in our household. If your TV, bread toaster, and microwave oven are all connected or plugged to a single power outtlet, you won't say that the TV is not working because the bread toaster is defective!!!!!! That's what your were saying in your above post.

Anyway, your WUR problem is solved. To solve the other problem about your FP running when it should not is much easier to solve or fix. Sit back and relax......look at the wiring diagram where the FP relay is located (cir.#106 in factory shop manual) or in other reference drawings. Do you understand how the FP relay works? Pop the front hood of your car and remove the red FPR. Locate terminal #85 in the FPR socket. This terminal in the socket is for the ground contact going to the AFS. There should be ground reading at standby!!!!

So how do you test it? Simple. Connect the test light to your car battery. Remove the ground and connect it to #85 (FPR socket). It should lit up. If it does not, you found the problem!!!!! The AFS is either defective or unplugged. Keep us posted.

Tony

[jwakil]

boyt011sc...I don't believe my WUR issue is solved. I went from no voltage at either pin to voltage at both pins now! How can that be? I'm not worried about my FP right now. I don't believe the fuel pump relay has anything to do with this problem? The WUR ground pin should go to ground. Now I read resistance of ~25ohms between the ground pin and ground, where as before it was close to zero.

[boyt911sc]

Originally Posted by jwakil

boyt011sc...I don't believe my WUR issue is solved. I went from no voltage at either pin to voltage at both pins now! How can that be? I'm not worried about my FP right now. I don't believe the fuel pump relay has anything to do with this problem? The WUR ground pin should go to ground. Now I read resistance of ~25ohms between the ground pin and ground, where as before it was close to zero.

jwakil,

Let's discuss this problem one step at a time. I really don't know how you're doing the test that gives you different results. It is confusing when you mentioned 'pin' to both pins (???). Which pin/s are you talking about? So an attached picture would really help this time. I have a fairly good idea of what you are trying to tell but I'm guessing.

A 25 ohms reading from your WUR is a good value (resistance). You had measured this value before in your ealier post. What you did not have before was voltage reading from the wire connectors to WUR.

What do you mean by 'The WUR ground pin should go to ground'? The WUR electrical plug could only go in one way!!!! This is to prevent the energized line to be connected to the ground wire.

Are you using a test light as I suggested earlier? Do you have a fuel gauge kit to use? Now that you have power from pin #10 (red/white wire), test the plug from the wire harness for power (use a test light)!!!! Keep us posted.

Tony

[jwakil]

Let me make it simple...Here's what I'm doing:

1. I disconnect the connector from the WUR (the one that has 2 female PINS).

2. I take my voltmeter and stick the positive lead into one of the pins, and put the negative to an engine ground, then I turn the key to run. Previously, I would get zero voltage if I contacted either of the two pins.

3. So with your help, I realize that the pin 10 on the 14 pin connector was loose and I fix that.

4. Then I repeat step 2. Now I read ~12V if I touch either of the female WUR pins!

5. THIS IS WHAT'S PUZZLING ME: WHY AM I GETTING 12V on both when I expect one to be 12, the other to be zero (ground).

6. I also measure the resistance from the female WUR pin that has a brown wire to the engine ground point. Before I was getting close to zero ohm, now its close to ~25 ohm (THIS IS NOT THE HEATER ELEMENT RESISTANCE! I ALREADY CHECKED THAT SEVERAL POSTINGS AGO and it was ok).