ECM POWER RELAY OPEN CIRCUIT

ECM POWER RELAY OPEN CIRCUIT 

17069 - P0685 ERROR

Electrical problems seems to stymie everyone, but repairing an electrical fault can be fairy simple if traced logically. The above error relates to a relay. Relays are just remote switches. Audi, Volkswagen, Seat and Skoda relays can give a fair amount of trouble because its push-in spade terminals may corrode, or they may even pop out of the relay plate due to shaking on bumpy roads. Their contacts may overheat and fuse together, or the spring inside may snap or jump off. Its solenoid can even burn out. Or its plastic enclosure may melt and block the switch mechanism from moving. But these are not the only faults related to relays.

Question?

Will Wallace shared this: 
Hey, I am a bit desperate for advice here, so reaching out.  Having a problem with my GF's VW Polo 1.4L 16V (BUD Engine). I have had to jump start this vehicle every 4 days or so. It will run fine, and then after about 4 days won't start, it either makes a clicking sound (sounds like a relay and wont turn over) when trying to start or starts beeping with the Engine light showing and the Park Brake light flashing (and won't make any sound when turning key). 

Connecting up a scan tool brings up Error 17069. Looking around the forums it seems like quite a common fault, with no real definitive solution. The battery measures 12V without the key in and then goes down to 8.5v when  the key is in and ignition ready. I've tried disconnecting the Plus Battery terminal and connecting a Volt meter to it and the battery post + and setting the DMM to Amps but its not coming up with any amp draw which I think is good (Not sure if I am doing this correctly though). It seems like something is draining the battery or the alternator isn't  charging it properly? I had a battery test done at a auto store and they said  it was fine and the alternator was charging it properly which is bizarre. I have posted this as it seems like a common fault and would be good to get  some advice. Thanks in advance.

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Answer!

Greetings  Will Wallace, so sorry to hear that you having so much grief with your Girlfriend's car. As much as I would like to help you, remote diagnosis without a full scan cannot always be accurate but I hope my thoughts on the matter may steer you in the right direction. The fact the you have  a scan with a 17069 manufacturer's specific code makes quite a difference. The generic code for this fault is P0685 and is relative to the  ECM Power Relay Control Circuit (See other codes below). From which  I can deduce that the Motronic ECM power supply relay itself  may be faulty, because of the 36-Open Circuit designator. However there are several possibilities. One possibility is that the solenoid winding is open circuit, and another is that its contacts doesn't close properly (open circuit), which is more likely. 

But there would also have been additional error codes, like 17072 or 17073. Considering either way, no rail voltage will reach the ECU, neither the injector coils, nor the injectors, etc, hence they won't function and the car would never start. So you need to prize-out the relay and do a physical check to make sure the contacts make or break as expected. The relay number is  J271 and will probably have the number 428 painted or stamped  on it. But before I explain how to do that, I want to raise a few points regarding the rest of your note. 

The clicking sound you hear, may or may not be the relay. If you said a single click I would agree that it's a relay, but since you said clicking, which implies several repeated clicks. It's most likely it's the starter solenoid that is chattering because their is insufficient voltage to keep it engaged, since you say it goes down to 8.5V under load. I'm inclined to favour this idea because it sounds like you battery is running down after 4 days and therefore not strong enough to drive the starter. But since you had that checked, try substituting another battery to make absolutely certain. 

The alternator could also be faulty and not charging the battery but I see you had that checked as well. Yet, it could imply that the diodes in the alternator are breaking down under load even though they function normal at idle. The battery voltage must be at least 11.5 volts constantly for everything to function as normal. Use your DMM and measure if there is any  resistance (ohms) between engine and body, there shouldn't be any. Also make sure you have a good connection  between the  negative battery terminal and the body. 

Regarding the amperage measurement, current is measured in series with the load. I don't think you should try to measure amps with your DMM because it may not be rated to measure more than 10 amps and may blow a fuse or damage its internals. Probably best to get a current clamp to measure current on cars. To return to the chattering, the starter could also have a intermittent power connection and could be the reason why it sometimes starts and sometimes not. Or the starter could be shorting to earth intermittently and draining the battery, hence the 8.5V. The best way to check this is to remove the starter and engergize it on a work bench to make certain it works the way it should. Before removing any control modules or relays from  the relay plate, make sure you disconnect the battery earth cable.

Relay J271 - Pin 85 and 86 are the solenoid terminal. Pin 85 is the 12V input whereas pin 86 is the solenoid earth. 
In the above image,  the only switch contact is between Pin 30 and Pin 87 which is normally open circuit.
When 12V is applied to 85  and 86, (normally happens when the ignition switch is turned  on) the relay 
should click and the power applied to pin 30 should exit on pin 87. If you hear the click but no voltage
 comes out  at pin 87, the relay internal contacts isn't making contact.
Try cleaning the contacts with fine sandpaper.

J271 varies from VW model to VW model, but once you have the relay out, check one of  its sides for the diagram of the pin-outs. It would look like the image on the bottom right.   The solenoid 12V supply will always be marked as 85, the negative always as 86, the normally open (N/O) contact as 87, or the normally closed (N/C) as 87a (if there is one). The pin marked 30 is always the switching voltage supply input. Notice that terminals of 87 and 30 are always larger than the other terminals because they carry a larger amount of current.  

Connect the relay solenoid to a battery with clip leads and measure the voltage at 87 and 87a, and verify that it switches over when you hear the relay click. Alternatively do a continuity test between pin 30 and 87, then again between 30 and 87a and make a note which one is open and which one is closed. Then connect power to the solenoid, pins 86 and 85 and verify that its continuity measurement switch over to the other pin. Unlike the image above, there may be even be more than 1 double pole double throw switch contacts on the relay depending on the model of your car. The Audi J271 is different to some VW's and has more terminals. It's also a good idea to check the relay socket wiring to or from the fuse box.  


P0685 - 17069   (ECM/PCM) Power Supply Relay - J271 - Circuit Open
P0686 - 17070  (ECM/PCM) Power Supply Relay - J271 - Short to Ground
P0687 - 17071   (ECM/PCM) Power Supply Relay - J271 - Signal to Positive

P0688 - 17072  (ECM/PCM) Power Supply Relay - J271 
Load Sensing Circuit - Open Circuit 

P0689 - 17073  (ECM/PCM) Power Supply Relay - J271 
Load Sensing Circuit - Short to Ground

P0690 - 17074  (ECM/PCM) Power Supply Relay - J271 
Load Sensing Circuit - Short to positive

P068A - (ECM/PCM) Power Relay Load Circuit - J271 - Opens Too Early  
P068B - ECM/PCM) Power Relay Load Circuit - J271 - De-activated Too Late