Here's 01m part 4
I've been meaning to post this info in much more complete format, but this info seems needed and I'm typing much of this info in tech help emails, and on the forums, or explaining it on the phone, so I'm gonna just post up what I can quickly, and reserve space for future additions when I have time.
A lot of this info is applicable to any solenoid. For instance EGR or Boost solenoids, or gasser injectors or maybe even applicable to a certain extent to diesel injectors on BRM and BEW. You just need to understand that air or gasoline is a fluid just the same as trans fluid.
A solenoid is a electomagnetic-hydraulic device to that electricty can be used to control fluid. Transmission solenoids have a specific funtion. To allow the computer to control movement of valve.
If you take apart a solenoid you would find a "winding" and a "pintle". When amperage is flowing through the windings it makes a magnetic field to move the pintle. The pintle is a a small valve that either blocks fluid pressure or vents it.
Electrical issues with solenoid (solenoid codes) .
If you have a solenoid code
then you may have a electrical problem with the solenoid. There are various methods that car designers can use for the computer to "see" a problem with the solenoid. These methods would include the computer actually measuring the amperage flowing through the solenoid circuit, voltage checks on the solenoid circuit, and the computer looking for a inductive spike when the solenoid is shut off. I don't know which method VW uses because Vw doesn't publish this info, but its irrelevant anyway. I do know this, VW's trans computers are real good at "seeing" a problem with the solenoid circuit. So if you don't have a solenoid code then you don't have an electrical problem with your solenoid, so put away your ohm meter and look elsewhere. Ohm checking when you don't have a solenoid code is a complete waste of time.
Now, you have to understand that the computer has no way of knowing if the problem with the circuit is actually the solenoid or the wiring between the computer and the solenoid. Problems like mouse chewed wires, corrosion in TCM connector, water in the solenoid connector, open circuit in the internal harness, bad power or ground to the trans computer or bad trans computer can cause these codes as well.
Lots of aftermarket sources define P0740 as TCC solenoid circuit (or similar definition). But, P0740 is NOT a solenoid code. Vagcom and other correct information sources define it as "Excess TCC slip" See 01m part 3. Dont try to diagnose P0740 as if it is a solenoid code. IT IS NOT A SOLENOID CODE. P0740 might be caused by the solenoid in some rare instances where the solenoid is stuck off, so see the section in this thread about "mechanical issues with solenoids". A stuck solenoid will not trigger a "solenoid code". A solenoid code is a problem with the electrical circuit relating to the solenoid, and a stuck solenoid will NOT affect the electrical portion of the solenoid. Please note: If your solenoid is sticking off it can cause P0740 but usually it will stick off sometimes and stick on sometimes. The symptoms for sticking on are so Radical and undeniable that you would never be concerned with the TCC stuck off. See stuck solenoid example #2 in the "mechanical issues with solenoid" section (post #2).
Diagnosing a solenoid code.
Diagnosing a solenoid code is real easy! As long as it's reoccuring immediately and consistently. If its not reoccurring consistently it can be just short of impossible.
Reoccurring immediately and consistently is defined as, "you clear the solenoid code with vag-com or your OBDII code checker and the code comes right back every time". If the solenoid code reoccurs immediately and consistently this usually means you have a open or short in the circuit and should be easy to identify with an ohm meter.
Please note: some transmission codes will put your 01m in failsafe or limp mode, and do not "reset" or clear, even if the problem is not currently evident or even if the problem has been repaired. You MUST clear these codes. If you repair a problem, and you are still in limp mode (failsafe) then you MUST clear the codes as repairing the problem will not take it out of limp mode. Maybe with enough driving or enough key resets it would but it would be better just to spin over to your local buddy with a code checker and have him clear it. Just because your transmission is in limp mode does NOT mean the problem is reoccuring. Limp mode is not your problem, Limp mode is the computers reaction to the problem. People always say, "yeah its doing it consistantly! Its doing it right now." Just because its in limp mode does NOT mean the code is reoccurring immediately and consistently.
I'm not going to explain how to use an ohmmeter but techniques include....
1. Removing the pan & ohm checking the solenoids. Drawback of this is it requires pulling the pan and this check doesn't check the integrity of the internal harness.
2. Ohm checking through the solenoid and harness from the computer with the computer unplugged. Drawbacks of this is that it requires a wire schematic and its hard to get to the computer. Benefits is you can identify problems in the harness.
3 . Ohm checking through the solenoid and internal harness from the trans connector. Due to difficulty in pulling the trans computer and not wanting to pull the pan, this is where I would normally start on a 01m.
Use the following pic to know where to ohm check.
Of course here is my website for more info.
Here's more info on this process and using the solenoid connector pinout from the link above.
every solenoid has 2 prongs. One for power and one for ground. To ohm check a solenoid at the solenoid, you would put you muliti-meter on the ohms setting, with one lead on power (one prong), and one lead on the ground (other prong). But this would require pulling the pan and it doesn't check continuity of the internal harness. So to ohm check the solenoid through the harness you do the same thing just through the harness.
Pin 2 on the solenoid case connector supplies power (voltage supply)
to the EPC solenoid. It says voltage supply on the chart.
So if you were checking the EPC solenoid resistance through the case connector you would put a lead on power to EPC solenoid (pin 2) and the other lead on the ground to the EPC solenoid (pin 8).
All the other solenoids use pin 1 as power (voltage supply)
so for to ohm check all the other solenoids you put one lead on pin 1 and the other lead on the pin that corresponds to a specific solenoid ground.
Now that I've used the term "ground" someone is gonna say "my harness isn't showing ground right now as I check it". Of course it isn't. These solenoids are provided with power all the time and when the computer wants them on, it grounds the solenoid. When the computer is commanding the solenoid on is the only time you will see ground on those wires.
Note: intermittent solenoid codes are difficult to impossible to pinpoint using ohm checks!
I would suggest if you don't have an ohm meter, or have lots of questions or don't understand this then you should just buy a solenoid and try it. Usually a solenoid code is caused by the solenoid except for the things listed above.
Solenoid position on the valve body is as follows.
2 N89 energized in 2nd and 4th to apply b2 brake
1 n88 feeds k1 clutch and b1 brake
5 n92 energized on each shift to cushion shifts
3 n90 feeds k3 clutch
4 n91 TCC solenoid
6 n93 pressure control solenoid
7 n94 controls apply to b2 brake
n89, n88, n94, n92 and n90 should ohm check at 55-65 ohms
n91 and n93 should ohm check at 4.5-5.1 ohms.
4-2-2013 Edit: N91 and n93 are fatter and cant be installed in the wrong location. Others are smaller and could potentially be installed in n91 or n93 spot. If you put the high resistance solenoid where the low resistance solenoid goes it will cause failsafe with a solenoid trouble code.
When the solenoid code is not reoccuring consistently it is very difficult to pinpoint the cause.
Intermittent code is defined as... You're driving along and the code triggers. You clear it and it doesn't reoccur for "some interval of time". IE till the next day, or till the next week, or 2 weeks later. You would have to do your ohm checks at the immediate moment that the code reoccurs in order to pinpoint the problem. Lots of times in these circumstances it is the winding in the solenoid shorting to itself effectively shortening the length of the winding which changes the resistance of the solenoid. Sometimes the windings can short for just brief intervals and then not short again till its hot or till some random bump in the road or just plain intermittently. Other times you might have a bare spot in a wire rubbing something and shorting to ground sometimes, or you could have a intermittent "open" in the internal harness or things like this.
If you have a intermittent solenoid code you should do a good visual inspection of the harness between the trans and the computer unplugging and inspecting all the connections, and if you see nothing then try a solenoid.
If I were involved in a intermittent solenoid code and the solenoid didn't fix it, and I found nothing in the other checks then I would attach a 4 channel oscilloscope to power and ground on the solenoid in question, and a amp clamp hooked to the scope, and drive it till it acts up.
Note: intermittent solenoid codes are commonly caused by water in the solenoid connector on top of the trans. If it happens when its raining or after driving through a puddle then open the connector and blow it out with compressed air or brake clean, clear the code and see if it reoccurs.
NOTE: Sometimes solenoid codes or other codes on a 01m do not clear on their own even if you have fixed the problem. In these circumstances you will have to clear them with vag-com. OBDII may work also.
MULTIPLE SOLENOID CODES on 01m
Lots of times folks will contact me and have multiple solenoid codes and want to know what to do.
1st. Understand that most of the solenoids in a 01m are powered from the same wire. They get this power from the computer and it has to pass through the cars harness and reach the solenoid connector. Then this power has to make it through the internal harness to each of the solenoids. Heres a diagram of the internal wiring to the solenoids. This is the diagram for a older jetta so it might not be exactly the same for all cars but the logic applies.
As you can see the last wire on the right powers all of the solenoids except for the #6 solenoid. So logic would say if you have a code for all the solenoids except for #6 then you would have a break in the harness of the car or a break in the internal harness before the solenoids.
Or if you had a code for all the 1-5 solenoids then logic might say that you have a break in the internal harness after the bridge to the 7 solenoid but before the 1-5 solenoids.
But there is a problem with this logic. The computer will sometimes only trigger codes for the solenoids that are on. If the trans went to failsafe before the codes triggered then it might not have triggered all the codes even though there is no power to them. Sometimes the computer isn't so great at giving the best info with multiple codes.
So what you have to do when you have Multiple solenoids codes is realize that most likely 4 or 5 solenoids didn't all fail at the same time. Its likely that a group of solenoids lost power at the same time.
First check that you have 12V at the solenoid connector on top of the trans. See my website (linked above) to know where the solenoid connector is and check the diagram above to see where to check for !2 V. If you have 12V on the power wire then you should ohm check through the solenoid connector for all the solenoids. If you have multiple soelnoids that read open checked this way then in all likelihood you have an open in the internal harness and your next step would be to pull the pan and unplug the solenoids and do ohm checks of the harness itself.
And of course dont forget that your computer must be powered up with 12V and have good ground to it as well. All the things I mentioned above can still be the cause of multiple solenoids codes (computer, car harness, trans internal harness, water in connector ect).
Well I've checked resistance with ohm meter and it seems fine. What do I do now?
While resistance checking or "static voltage" testing is ok and will identify most problems every once in a while you get one that checks good and your at a loss of what to do. In certain situations, mainly either a intermittent or a case of poor connection you will need to amp check to identify a problem in a solenoid circuit, to fix your solenoid trouble code (or codes). In these cases the next step is to AMP test the solenoid circuits. I usually use a amp clamp, sometimes with a oscilliscope, but a multimeter that can check amperage might be good enough.
There are two methods.
1. Amp check from computer, through cars harness, through trans internal harness and through solenoids. Drawback: You have to pull computer, and you have to have a wire schematic to see which wires to hook to.
2. Amp check at solenoid connector on top of trans, through the internal harness and through the solenoids. Drawback: If your problem is in the cars harness between the solenoid connector and the computer then this check isn't going to find your problem. Benefit: Its easier to do.
If your getting one specific code, relating to one specific solenoid circuit then jump power to the appropriate pin in the diagram above. Then ground the appropriate pin to run amperage through the circuit. for instance.. you have a code on for n88 solenoid then jump battery voltage to pin 1 and ground to pin 3.
I do this with a solenoid connector that I've acquired (through a 5 speed conversion). I plug it in to the solenoid connector, and jump battery voltage and ground to the appropriate pins. If you dont have a solenoid connector you can improvise something either a "female" round pin connector that you take apart to use the "pin" in order to connect to the male "pins" inside the solenoid connector or maybe if you have some tiny alligator clip test leads in your tool box, that might work too. Simply touching the pins with some type of probe might work too, but it's tight in there and will be hard to do this and get a good connection.
NOTE OF WARNING: The low resistance solenoids (4.5 to 5.1 ohms see ohms of solenoids above) CANNOT handle lots of amperage running through them. They WILL heat up and burn out if you simply hook up power and ground and leave it connected.
When the computer turns these "ON" they control the amount of amperage through them with Pulse Width Modulation. If your amp checking them you need to do it quickly, just tapping the wire to connect the ground. This will make it difficult to "see" your reading, if your using a meter. You might want to just NOT test these this way. Of course if you just have one solenoid code relating to a low resistance solenoid and your resistance checks have failed you then of course you have to. I use an amp clamp and a scope in this circumstance as with my scope I can "scroll" backwards to see what the readings were.
How many amps should it have? AMP tests are dependent upon your battery voltage and resistance of the solenoid. Ohms law is V=I x R. Read up on ohms law here--->http://en.wikipedia.org/wiki/Ohm's_law
Use your meter top get your acutal battery voltage first, then insert battery voltage and the resistance of the solenoid, into the formula, and do the math, to see what amp reading should be. If its low then you need to find out why. ie bad solenoid, bad connection, bad harness ect.
EXAMPLE for instance:
You have code for n88. your battery voltage is 12.6. N88 solenoid should read 55 ohms. You've done voltage tests and ohms tests till your blue in the face. No solid failure stands out, so you amp test. Lets say for instance you have the computer out all ready cuz you swapped it out with a buddy's computer or something. So you unplug the computer jump 12v to the power wire for the solenoids and you jump ground to your n88 ground wire, while measuring amperage.
we insert our numbers into our formula V= I x R
V = 12.6 volts
R = 55 ohms
So after a little high school algebra our amperage should be .2 amps (rounded). Lets say for this example our amperage was .5 A. So we know our system, when "LOADED" cannot handle the correct amperage. Yes the resistance and voltage checked fine cuz we checked till we were blue in the face. In a actual working circuit (loaded) the amperage can be low even when YOUR meter checks the voltage and resistance as ok.
But where is our problem? Is it....
1. In our cars harness?
2. In our transmissions internal harness?
3. In our solenoid?
4. In a connection somewhere?
5. To hell with these things I'm gonna drive this car in the demolition derby!. Failsafe is ok for Dem. Derby cuz I'll shift it manually!
We don't know because we checked all the way through the circuit from the computer to the solenoid. Our amp reading shows us there is a problem but NOT where. So the next step would probably be to amp check at the solenoid connector. So continuing the example from above lets say we amp check at the solenoid connector for the n88 and it shows the correct 2 amps. At this point we would know the problem lies in the harness between the computer and the solenoid connector. A good check now would be to use a spare solenoid or take one out of your trans and jumper it to the harness and amp check again from the computer. Do this BEFORE opening up the harness looking for corrosion or partial broken wires etc! And the reason why is because if it checks good then in all likelihood then with these results the problem would lie in the connection between the cars harness and the solenoid connector. I've had transmission solenoid codes many times be due to round connectors that the female side was "stretched" out. This has been the most common issue that caused me to have to go so far as amp tests, but corrosion or partially broken wires cause this scenario also.
But lets say that our check at the solenoid connector DID NOT show the correct amperage. Lets say the amperage showed .5 amps. So at this point we can assume the cars harness is good and that the problem lies in our internal harness or n88 solenoid. To pinpoint the problem we would then pull the trans pan and amp check the solenoid without the harness. No need to remove it to do this , just jumper voltage to it "in place" and and if it checked good then we can say, through the process of elimination that our harness is the culprit.
None of this is super simple, but this is what it takes to do DIAGNOSIS. Diagnosis means knowing ABSOLUTELY, positively what the problem is. It doesn't mean, you have a solenoid code and so you slap a solenoid on it, or slap a harness on it or you throw a computer at it. This is why fixing cars is tough. This is why everyone thinks stuff is too expensive or that mechanics are incompetent. If All this is too much for you then just slap some parts on it. Honestly in the real world lots of times slapping some parts on is easier and cheaper than doing all this.
And for those who have multiple solenoid codes and end up at the amp check process, you might have to do this amp test for all the solenoids that you have codes for. Yes, its alot of work. But if its a problem in the power feed circuit most likely you will identify the problem on the first solenoid circuit you amp test and all the others might be the same. (hopefully??)
I'll probably be editing this and adding some amp check pics next time I go through this process.
Definition of terms.
1. Valve -- NOT A SOLENOID. The term solenoid valve although true in the most literal sense is confusing. I just want to differentiate that a valve is not the same thing as a solenoid. It would probably be best to call a solenoid a solenoid and not a solenoid valve.
2. Solenoid-- electomagnetic-mechanical device so that electricity can be used to control something mechanical (valve, relay switch ect) In a transmission electro magnetic force is used to control a mechanical pintle which controls trans fluid pressure. Other solenoids (boost or EGR, ect) use electromagnetic force to control a pintle that controls vacuum.
3. Fluid-- AIR, vacuum, or liquid.