Note: the pump comes on when the car is started from cold and turned off after 5 seconds. So the pump activates as expected.

Five seconds is certainly not enough time to help heat the cat with SAI. Is that 5 seconds consistent? If so, the relay is probably operating correctly under control of the ECU, but being shut off way to early. If you had/have access to VAG-COM, the output test for SAI would verify that the ECU can turn on and off SAI. I don't know how the SAI is programmed to run, but I assume the coolant temp is checked. Maybe the CTS?

 

Oh the 5 seconds was from a youtube video I watched - the purpose was to hear if the SAI SAI pump turned on or not. If the pump didn't even turn on, then I was suppose to check the fuse and the relay. Since the pump turns on the fuse is fine. But I looked at the fuse anyways this morning in the ECU box and was fine. I did some more research and relay 373 in the ECU box maybe the SAI relay. Going to test that when I get home.

I do not have access to VAG-COM, unless the free VCDS-Lite version would work?.
Or do you happen to have VAG-COM and still happen to live in Yorba Linda? If so, I am fairly close by and can buy beer or beverage of your choice, if you can help me run the VAG-COM tests

 

The 373 relay in the ECM box is the SAIP relay.

The circuit to the SAIP is: battery to 40A fuse, fuse to relay contact, contact to SAIP. The circuit doesn't pass through the ignition switch, or even enter the cabin, largely because it pulls so much current. The relay coil is energized by the ECM. Like the other ECM outputs, (ignition switched) +12 volts is wired to one side of the coil, while the ECM controls the negative side; it pulls it to ground to energize the relay.

You can jumper the relay contacts, but do so with great caution--there will be a big spark when you open the circuit. I'd be more inclined to remove the relay cover, then use a stick to manually close the contacts. That will give you an opportunity to inspect the relay contacts.

My experience with the SAIP relay in my (now gone) Fresco Green 01.5 Passat, owned its whole life, was that the SAIP relay contacts were burned up beyond repair after about 10 years. It stuck closed and the contacts looked like swiss cheese.

I'd strongly recommend replacing the relay. It's a very common automotive relay, and inexpensive. The OEM version has a 680 ohm resistor across the coil for surge suppression, but you can get along without that. However, do not use a relay with a surge suppression diode in it; the ECM doesn't play well with the diodes.

 

The OEM version has a 680 ohm resistor across the coil for surge suppression, but you can get along without that. However, do not use a relay with a surge suppression diode in it; the ECM doesn't play well with the diodes.

I'll take your word for that, but we use solenoid coil driver ICs which includes reverse-biased diodes, to protect the electronic switches from high-voltage spikes when the coil current is cut off, at least that's the explanation.

 

I can't see how a diode in a relay could have any negative effect on the ECU.
A high voltage spike is generated by the collapse of the magnetic field when the circuit is opened,
a diode can be used across the coil to absorb these spikes, and prevent them from affecting the control circuit.

I suggest you use the same type of relay as the original.

 

I can't see how a diode in a relay could have any negative effect on the ECU.
A high voltage spike is generated by the collapse of the magnetic field when the circuit is opened,
a diode can be used across the coil to absorb these spikes, and prevent them from affecting the control circuit.

Tom and ylwagon/fbwagon,
I read the "no diode rule" on this forum years ago, but that poster didn't say why. But DIN automotive relays are commonly offered with diode, resistor, or no surge suppression, so there must be some reason to use resistors. You made me do some research...

It turns out the diode won't do any harm to the ECM, but it does delay the relay contacts opening (by milliseconds), since it creates nearly a short circuit across the coil, thus delaying the collapse of the magnetic field. A resistor won't control the voltage spike nearly as well as a diode would, but it does allow the magnetic field in the coil to collapse almost immediately, opening the contacts. The coil energy dissipates over a longer period of time.

So, a relay with a surge suppression resistor might last longer because the contacts open faster (and more decisively?), but with the age of our cars, I wouldn't sweat it. A relay with a diode would be superior to a relay with no surge suppression with regard to protecting the ECM.

Thanks for asking!

 

Hey guys, I powered the SAI pump directly from the 12v car battery by hooking up a couple some alligator clips. The pump came on, and I felt faint air. Moving the tube (058133817D) changed sound (loud vs low). Decided to take the tube off and it broke completely at the top connector portion.

Walked to the nearest autozone, they didn't have an replacement, or any other appropriate sized tubes that I could attach with clamps. So I jerry rigged the broken tube by shoving in a tight fit fuel line tube and lots of electrical tape. Made sure air didn't leak easily.

Deleted the following codes P0411, P1114 & P0140. Maybe the last two were triggered during my fix? Hoping its all fixed, will know soon enough I suppose. Ordering a replacement hose as a backup.

 

Hmmm.... fbwagon. Not bad Emry.

 

I had a job offer in San Marcos but turned it down when I saw the house prices in that area. Then I ended up in a shithole Michigan with single digit temperature :crazy:

 

The San Diego area climate is generally pretty decent. Today it's about 73F and dry in Fallbrook (which is actually about 45 miles North of actual downtown SD). However, the next time there is a big fire or when the San Andreas finally shakes the place down, swoop in and pick up a bargain.

 

^^ I agree with everything you said but I would add that the spike of current going through the resistor will actually be 'absorbed' - as heat - while a diode will not absorb the energy but will simply let it pass through to the extent that a diode is a true 'short circuit'. The diode is not a super-conductor of course, so it will have some resistance and there is usually several hundred milli-volts of forward voltage drop through a conducting diode as well, but in general, the diode will simply 'turn on' and let the current flow through while the resistor will 'absorb' the current with a I*R voltage drop.

To really know the best solution would require knowing the entire circuit involved, including the characteristics of the connectors and wires, etc. I wouldn't sweat it unless you are continuously burning up relays in which case I would try a different type or brand. For folks who do worry about this stuff I think the best approach would be to get an OEM relay or equivalent since some VW engineer probably went through this exercise already and came up with what he/she thought was the best solution for this particular case.