Egr wiring tests

[Dean_]

I have 1.8 tdci with an egr fault.

I have so far tried new egr motor, new egr valve assembly and I still have fault code p0406 coming up so I'm thinking it's either wiring or another sensor giving wrong information to the ecu? 

At the moment I have to run with a egr blanking plate in other wise I have no power. The valve is free moving, clean and de coked.

Any suggestions, test procedures, test voltage and resistance readings or wiring diagrams would be greatly appreciated 

[Tdci-Peter]

8 hours ago, Dean_ said:

have so far tried new egr motor, new egr valve assembly and I still have fault code p0406 coming up so I'm thinking it's either wiring or another sensor giving wrong information to the ecu? 

At the moment I have to run with a egr blanking plate in other wise I have no power. The valve is free moving, clean and de coked.

Any suggestions, test procedures, test voltage and resistance readings or wiring diagrams

The original EGR actuator on my 2006 1.8 had a basic electric motor and a pot (potentiometer) for position feedback.

The motor is on pins 1 & 5, and should have very low resistance (<2 ohms) with a multimeter, but the reading will jump about violently if the actuator quadrant wheel is moved by hand, due to motor back EMF. But it should settle back to a low resistance whenever the movement stops.

The Pot is between pins 6 and 2, with the pot wiper on pin 4. My pot was about 5k end to end, and the wiper resistance varied between about 1.5k and 3.5k as the quadrant wheel turned.

You can also test the motor by applying voltages up to 12v to it (1 = +, 5= -), ideally with a variable power supply. It has a spring return, so power off should always make it snap back to the closed position. (The drawing shows 1+ & 5-, but my hand scribbled notes seem to say 5+, 1-, but a bit of reverse power will not damage it, just won't move.)

The Chinese EGR actuator I replaced my dodgy old Ford one with this year, has an electronic sensor. Resistance readings are almost meaningless. At first I though it was duff, but when 5v was applied to pins 6 & 2 (2 = +), it sprang to life and gave a sensible voltage output on pin 4, just like the pot version would with 5v applied across it. In theory an electronic sensor may be better than a mechanical pot, but it all depends on the quality. It is Chinese, so I will wait and see! The actuator is in a tough location, high temperatures and massive vibration are the norm.

I have been repairing mine since 2012, it worked for a while each time, then started playing up again in a year or so. So I am very familiar with its internals. Though only the actuator, I have not had the inlet manifold off to check the valve part. But that has always seemed to move smoothly.

I have done a post somewhere with pics, but have lost it. I will look a bit more later. I can find it via the attachments.

 

 

 

[Tdci-Peter]

9 hours ago, Dean_ said:

wiring diagrams

Found the post:

 

Also there is a diagram of the valve & connector:

All 5 wires go straight to the ECU. Though I suspect they may go via that big connector on the back of the engine. The wiring diagram does not show that one.

I have just noticed your car is S-Max, so wiring colours may differ. But I suspect most engine bits are the same. ECU software may be a bit different though. Please let me know if there are obvious differences.

Since you have changed the valve & actuator, either there is a fault in the new actuator, or there is a fault in the wiring, or even (hope not!) in the ECU.

With the actuator removed from the valve, but plugged back in to the car wiring, you can see the power off test. Just cycle the ignition on then off. It should do a series of full actuations, probably to clean the valve, then hover in one or two places, then snap shut. I have a feeling that this test is what puts the EML on if it fails, it seemed that way on my car anyway.

The EML is still not an MoT fail on a 2006 diesel, but a visible blanking plate in the EGR might be, though only if an eagle eyed tester spots it and knows what it is!

Regarding other sensors, does the EML & DTC appear when blanked? On my car I could still get errors while blanked off. That rather narrows it down to the EGR valve.

When blanked, the valve is almost always either full shut or full open while driving. When not blanked, it mostly hovers in mid travel while idling and cruising. It closes in over-run or at more than about 50% of full power, or at over 2500rpm. The sensors that control this are the MAP, IAT2 and the MAF. The airflow through the engine can be estimated from MAP, RPM and intake air temp (IAT2) in the air duct just before the manifold. This estimate includes the EGR flow. The MAF measures air into the system, prior to EGR flow. So the difference should be the EGR flow. However this is rather approximate, subtracting a rather imprecise MAF reading from a complex computed estimate is obviously dodgy. Since I get no errors when the valve is blanked off (if the actuator is working ok), and the ECU knows this as it drives the EGR hard open to try to get the flow it wants, then it seems the ECU accepts the error. But it does not like it when its power off test fails, or the pot reading does not match the motor drive voltage.

 So the above rather complicated paragraph means that I think most EGR DTCs on this engine are directly related to the valve or its wiring.

[Dean_]

Thanks for all the info,  I will have a pike around this weekend and let you know what I find 

[Dean_]

Just to add I have ran with egr blanked for sometime with no fault codes so presume it is a fault with he valve or wiring rather than a lack of egr flow being picked up by other sensors 

[Dean_]

Also do you know and volt reading that should be supplying the actuator or and tests for the loom? 

Thanks again 

[Tdci-Peter]

36 minutes ago, Dean_ said:

do you know and volt reading that should be supplying the actuator

The motor is a 12v unit, though about 3v is enough to start it moving, and 6v to 10v is enough to move it all the way, just against its internal return spring, if I recall. The output from the ECU will be a 12v nom. (14v more likely in practice) PWM signal, at about 1kHz from the tone I can hear when it is operating, but a multimeter will read the average voltage, which is what the motor also responds to.

Testing the loom can be a pain, as the connector at the ECU is usually protected by a security bolt, and I do not have a diagram for an S-Max ECU. If it is the same ECU as in the Focus, (Siemens/VDO), then there is a diagram on this site, and I can find pin numbers etc.

Back-probing the EGR connector while connected and running may yield some clues. Also Forscan can read the EGR desired position, though on my car I don't think it can read the EGR pot feedback signal for some odd reason. I can give more info on Forscan if needed. It is probably the most capable DIY system that is available for Fords.

[Dean_]

So had a quick look at the the old original actuator last night and when I opened it up in was full of carbon dust, once cleaned I could then power the motor on the bench and it would return when power was removed. But when I plugged it in to the car and left loose I still had no moment at any point???? 

[Tdci-Peter]

1 hour ago, Dean_ said:

I could then power the motor on the bench and it would return when power was removed. But when I plugged it in to the car and left loose I still had no moment at any point???? 

Mine moves when the ignition is turned off, even if the engine is not started. It should move within a minute or so of starting the engine also. It sounds like a wiring fault. Does you car have that big connector next to the EGR valve?

If so the wiring probably goes via that to the ECU. I have no diagram of it, but it should not take too long to do a quick continuity test on all connections to find the EGR ones.

It is just possible the feedback pot is giving a high signal, which is preventing the ECU from energising the valve, but that should cause an error code. To measure voltages on live wiring on the car, google back-probing, if you have not already done so.

[Dean_]

Quick update, I haven't had time to do any back probing but with the new actuator still fitted I did disconnect the battery for an hour to see if it would reset and parameters and fingers crossed it is yet to throw the  eml back on. I am still running with the blanking plate in as it drives alot better like most cars do when the egr is blanked off. 

So hopefully my problems are sorted. Tanks for all your help Peter. Greatly appreciated! 

[Dean_]

Unfortunately, bad new, the eml has come back on with egr related code. Peter, if you have any spare time would you be able to give me voltage readings for each pin off your cars egr loom plug both when running at idle and just Ignition on engine not running.

Thanks again 

 

[Tdci-Peter]

6 hours ago, Dean_ said:

would you be able to give me voltage readings for each pin off your cars egr loom plug both when running at idle and just Ignition on engine not running.

I had a look at quick look at parts lists for the S-Max & Focus, and although the EGR, Injectors and fuel pump are all common, the ECU has a different number. So there may be some detail differences. From one photo, it looked like it was a completely different unit, but a wider search shows them both to be the Siemens / VDO part, so the difference should not be great.

I can be 99%+ sure of the position feedback readings:

Vref (2) is +5v steady, running or just Ign on. (I would expect it to be pretty close, say 4.8v to 5.2v).

Vgrd (6) is 0v steady, running or just Ign on. (again pretty close, +/- 0.2v from battery negative).

Vout (4) is typ 0.6v steady, engine off, Ign on. This will vary rather more, say 0.4v to 0.8v, it depends on just where the valve closed point is, and may change a bit within that range each time the valve moves and then returns to rest. But it should be a steady reading while the valve remains closed.

Vout will be much more variable once idling. Typ 1.5v to 3.5v I would say. The valve is almost constantly moving to try to maintain the desired flow rate. Unless EGR is blanked, when it will be 3.5 to 4.5v, and fairly steady, as the valve is driven full open.

Also the valve may remain closed for a few seconds to a minute or so right after a cold start.

The importance of the steady reading is that a varying reading while it is expected to be steady would indicate a bad connection.

The motor drive signals (1 & 5) I am not so sure of, and they could vary with ECU type. I have measured the voltages needed to drive the motor, but not on the car. I would guess one of the lines will be near battery positive while Ign is on, and other will be driven to a lower voltage to energise the valve. But it is possible that it will be the other way round, one line near battery negative, and the other driven to a higher voltage to energise the valve.

What I can say is that the voltage on both lines will be the same (both ground or both battery positive) with Ign on & engine off, and at any other time while the valve is closed.

Also when the valve is operating (engine idling), there will be a rather variable voltage of 2v to 4v between the two.

I have just re-checked my old (OEM) EGR actuator. Pin 5 is +ve, and Pin 1 is -ve, to drive the valve open. And the voltage to drive the motor is lower than I thought, 3v was enough to move the actuator to the fully open position.

 

[Dean_]

Just a quick update, sorry it's been so long.

With gentle persuasion you can remove the brass internals of the egr hosing to clean the back side of the valve. Just make marks before removing as it has to be in the correct rotation otherwise will confuse the control motor.

Many thanks to tdci-peter for all the information and help, much appreciated 

[Tdci-Peter]

18 hours ago, Dean_ said:

With gentle persuasion you can remove the brass internals of the egr hosing to clean the back side of the valve.

Was this the brass bit you managed to remove:

It looks quite well peened in to me, but might come out with the right sort of persuasion, maybe?

Did cleaning the inside of the valve cure the problems?

[IiroH]

Hello, I know this in an old post, but it has very valuable information for me. I have a 2008 Mondeo Mk4 with 1.8 tdci and with an egr fault P0490. I would have a few questions.

I removed the EGR actuator and the barbell shaped small part that mates with the actuator motor gear is intact. The valve seems to move well without restrictions. I have had a blanking plate in place for more that a year without fault codes, until this week. I have not opened the EGR valve inself, we all know how much work that requires.

Now, the questions:

1) If I remove the actuator, but leave the electrical connector in place, and start the engine, should I still get a fault code, if the fault code is caused by inadequate travel range of the valve itself ? What I mean is that, if the actuator is ok, and the motor can freely move as it likes (since it is mechanically disconnected from the valve itself), should the fault code disappear ?   Assuming again that there is nothing wrong with the actuator motor ? I guess the motor potentiometer feedback to ECU only tells about the position of the motor, the motor would not notice if it is completely disconnected from the valve itself ?

2) More or less the same question from other perspective: If I still get P0490 in this test, would that mean that my actuator is faulty ? Any more recent experience with the Chinese actuators? 

3) Again, If the P0490 is caused only by inadequate travel range of the actual valve, due to carbon build-up, could I solve the problem by removing the barbell shaped part and leaving the blanking plate on ? Motor would be disconnected from the valve itself and blanking plate would prevent exhaust gas flow into the valve.

I notice now that I should first verify if the actuator motor is moving at all in the ignition-on test described above. Now when I think of it, I have no solid information that it works at all. When you move the plastic gear with your hand, it moves easily and the return spring works as well. I will check this during the weekend and report on that.

Thanks for any help and advice you can provide.

  

 

[IiroH]

Ok, no replies and no interest here.... but I will answer myself since I found and fixed the problem in my car. I just thought I will report if this will help someone.

So, I removed the actuator unit, and placed it below the windshield, so that I could see what the motor is doing when you turn the ignition on while sitting at the drivers seat. Connector was naturally connected for this test. Nothing happened, and I thought the actuator is broken. I removed the actuator to do an additional bench test, to make sure that the actuator is really broken. I connected +12V to pin 5 (see pin order above) and ground to pin 1. This is the correct pin order at least in my Mondeo, even though the connector drawing above seems to have a small "+" sign besides the pin 1 lead. 

In the bench test the motor was not reacting at all, so I still thought it is broken. Just in case, I thought I will open the black plastic end cover of the actuator to see what is inside and if I can see some visual damage.  What I found out is that there are two male connector studs coming out of the motor and theses mate with sort of female counterparts in the black plastic cover part. Unfortunately I was too exited to remember to take photos....

Well, anyway, when I connected  12V and ground directly to those studs coming out of the motor, the motor worked fine. And it turned out that the "female", fork shaped counterparts in the end cover part were just too loose to make proper contact with the studs sticking out of the motor. I used a small screwdriver the tighten the gaps in the "forks" and, voila, actuator started working perfectly.

I reconnected the actuator to the car connector, and now the motor reacted properly when I turned ignition on.

 

If you encounter a similar P0490 problem, my suggestion for the trouble shooting actions is as follows

 

- Remove actuator, check if the valve itself moves easily and from end-to-end without restriction, see youtube videos about this

- Check that the barbell part is intact, many youtube videos show that this part may be broken and this prevents the valve from moving

- If you use pliers to rotate the valve itself, as explained here and in many youtube videos, be carefull not to pry out one the lockíng circlips of this "barbell" part, this happens easily and if you drop it, with 90% certainty you will never find it, it may be a good practice to place a cloth or something to catch any of these small parts if you accidentally drop them

- If valve and barbell are ok, check actuator motor operation as I explained above, first with the actuator connected to the car and then in a bench test

- If motor does not seem to work, open the black end cover of the motor to check if motor reacts when connected directly without the black end cap part 

- If motor works in this test, tighten the interconnection "forks" and retest, it not, then the motor is really broken and you need a new one

 

Some additional notes:

- After fixing the problem, I retested the actuator in the car. When I turned on ignition, the motor turned immediately approximately to a half-way position, then moved slightly forth and back a couple of times, and parked to a fully open position. I assume this is natural since I have a blanking plate and no exhaust gets into EGR, so ECU tries to maximise the flow. As explained above, at least in this car, this does not cause the engine light to turn on.

- To me it seems the "start-up" test that the ECU makes when you start engine, does not really test the extreme positions of the valve (fully open and fully shut), so even if there is slight build-up in the valve itself, and the shut position of the motor slightly changes, I doubt this would result in P0490, at least not if the build-up is not excessive. My car has now almost 300.000km and I do not think the EGR has ever been replaced.

- If your ERG valve itself is stuck, or it´s movement is heavily limited due to build up, and you have a blanking plate, removing the barbell part completely would probably remove P0490 error since motor could move freely since it would be disconnected from the valve itself. The motor feedback to ECU is based only on the motor movement; if motor moves as instructed by ECU, no errors will result. ECU does not know if motor is really connected to the valve itself. Or that is what I believe.   

 

 

 

[Tdci-Peter]

On 4/3/2023 at 8:15 AM, IiroH said:

And it turned out that the "female", fork shaped counterparts in the end cover part were just too loose to make proper contact with the studs sticking out of the motor. I used a small screwdriver the tighten the gaps in the "forks" and, voila, actuator started working perfectly.

I am afraid I missed your 28 March post, I have been over occupied with other stuff! I had exactly the same problem with my EGR actuator, the fork connections to the motor, and the connections to the resistance element in the pot both failed at various times. After several repairs, I ended up replacing the actuator with a Chinese one, which has worked well. It has an electronic angle sensor rather than a pot, which can be a more reliable solution in an area of high vibration and high temperature.

Your logic about testing with the actuator removed is correct, it is self contained with motor and sensor. However the ECU does know that the EGR is blanked, this is obvious when driving as it slams the thing from full open to full closed in the various driving conditions, whereas when unblanked & operating, it holds the EGR in mid positions a lot of the time. The ECU measures EGR air flow indirectly by comparing MAF readings with a computation based on RPM, MAP & Intake Air Temperature readings. But this does not seem to bring up error codes on the 1.8. It tests the EGR on each ignition off, comparing motor actuation level with position sensor readings, and this seem to be what causes the error codes if the motor or sensor fail.

I did a write up with photos in:

The spelling error in the title is not mine! And I can not correct it, so it may not be found easily by a search.

 

 

[kevoB]

On 2/17/2019 at 6:22 PM, Dean_ said:

Just a quick update, sorry it's been so long.

With gentle persuasion you can remove the brass internals of the egr hosing to clean the back side of the valve. Just make marks before removing as it has to be in the correct rotation otherwise will confuse the control motor.

Many thanks to tdci-peter for all the information and help, much appreciated 

Hi,

How did you manage to remove the brass internals please?

I would really appreciate the help with this one.

[Tdci-Peter]

On 1/13/2024 at 4:42 PM, kevoB said:

How did you manage to remove the brass internals please?

Dean has been absent from the site for a while.

On mine it looks like the aluminium is peened over the brass EGR, but it is hard to see. If you are sure there is a problem with the valve itself, then paring away the aluminium around the edge of it with a Stanley knife or similar, might reveal if it is peened in, and help release it.

I did not try very hard to remove mine, there was no point in risking damage to it as all the problems were in the actuator unit.

But first check if it seems jammed or very sticky, and if so try some suitable cleaning fluid, maybe injected via the inlet hose hole with a syringe.