Wow .... I'm not sure. From your description is sounds like the problem is somewhat intermittant ...... so I doubt it is a fuse. Then again the modern fuse box on the W210 models virtually eliminates the fuse problems of eariler models .... so if your 1995 has the old style fuse box with round style fuses then perhaps checking the fuses and cleaning them might be worth a try. When you swap the two valves does the intake flap work all the time? If it does then I would consider taking a chance and purchasing a new valve because electronic issues are difficult to track down and it is possible that the valve is intermittantly bad either on the vacuum side or the electronic side. If swapping the valves doesn't correct the problem for the intake flap operation then the problem is probably electronic. The problem could either be in the control wire(s) from the ECU to the valve, or it could be the ECU itself, or it could be a bad sensor or wiring connecting one of the sensors to the ECU. I don't know what sensors drive the movement of the intake flap via the ECU. Trouble shooting such a problem requires a manual and wiring diagram to do it right. Good luck.

David Roseman
Long Beach, Ca

This past Friday I had a mechanic (thanks for the recommendation Terry) run a diagnostic on the computer system. He didn't provide any concrete conclusions, but recommended that I replace the coolant sensor and voltage relay. He further stated that with a bad voltage relay, the air/fuel mixture becomes very rich, which would cause my poor fuel economy. The problem is that I don't know what he means by voltage relay. I called him today and, I guess being to busy to talk, he said to ask at the dealership and they will know immediately. Is it the ovp relay he's referring to? I tested the ovp as per the instructions at Help!! Need OVP plug schematic!, post #58, and got supply voltage to pins 30a, 87E, and 87L just as it describes. Could he have meant the EGR relay? My EGR valve hasn't worked since 4 or 5 days ago. Would the EGR relay control or have any effect on the intake flap? Unfortunately, I don't know which coolant sensor to check/replace either? I was told that it is not the two-pinned blue one to the left of the fuel filter, and I recently replaced the 4 pin sensor beneath the intake manifold with no improvement. Are there any others? I've heard there are three coolant sensors, but I'm not sure if my car is set up the same. Since a coolant sensor may play a significant role here, I figured I'd mention that I recently noticed that my auxiliary fans don't work either. I tried jumping the two pin coolant sensor, but that did nothing. Sorry for the cluttered information. I don't mean to try to have all my cars issues solved in this thread, but I just thought that knowing this could in some way help get to the bottom of this.

Did you got to to Medi? If so, he was probably refering to the OVP relay I'm guessing.

Can't remember, does your AC work? If not that may be why the AUX fans dont come on as they are there mainly to cool things n stop and go traffic when there is little or no airflow.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Yep. AC blows, but not cold. The thing is, I thought that if I jumped the two pins on the blue coolant sensor, the fans would run constantly, yet they do not. I suppose it could be something else. Anyway, I'm working on an other coolant sensor, so if that doesn't work, I'll check the ovp wiring next. Does anyone know where to get a new plug (126 540 30 81) for the 4 pin coolant sensor (008 542 32 17, listed as water temp. sensor)? If not, is it possible to break it open in a way that it is still usable? The wiring is degrading all the way to the plug.

You need to connect a wire to the 2 sockets you pulled off the pins, not the pins themselves. The sensor is just a switch. So by jumping the wires with a short piece of wire you are removing the switch. Does that make sense? You are talking about the one just behind the upper radiator hose, correct?

__________________
1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

I had the sockets connected to the pins with a wire wrapped around them at the bottom. So unless the the pins were no longer able to conduct electricity, it should have closed the circuit. Sorry, but for whatever reason, I forgot to mention that it was still plugged in. I tried it again, and after spinning the fans around with my hands, I got one of them to work. Or it just takes more time to kick in than I thought. That is correct.

Right now I'm trying to test the ELR relay (N8) with some very helpful documentation sent to me by Phil. As you can see from the picture, it is asking me to test the resistance between connection 10 and 12 (under Tester/Test Connection). The problem I'm having is that neither the pins nor their proper connectors are labeled as such. Instead, it's labeled: 31, 15, EL+, GM-, GM+, TF, TD, and DI. Does anyone know where 10 and 12 should be? For that matter, does anyone know what connections any of these numbers on the attached page are referring to? Is there a pattern or something by which I can determine the correct connections? If this helps, L3 is the speed sensor, N8 is the ELR relay, and N37/3 is the ARF/variable intake manifold system control unit (EGR relay I think).

Attached Thumbnails