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Discussion Starter · #21 ·
well if i knew what terminal everything came from nothing would be a problem. how are you supposed to tell what terminal a wire comes from when the connector prevents you from seeing anything?
 

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well if i knew what terminal everything came from nothing would be a problem. how are you supposed to tell what terminal a wire comes from when the connector prevents you from seeing anything?
This makes no sense. The connector is what tells you which terminal. Let's try this a different way...

Does your mystery wire come form the knock box or the ICM?

With the (insert source of mystery wire here) sitting flat on the mounting surface on a table with the connector facing you start at the left pin (#1) and count to the right until you get to your mystery wire.
 

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Discussion Starter · #23 ·
Im not sure about your knockbox connector, but my knoxbox connector is just a bundle of wires that runs into the connector. There would be no telling what wire came from what terminal.

By ncbrock at 2012-01-10
 

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Discussion Starter · #26 ·
ive got that one and a golf\jetta one. Unless you spend a lot of time studying the current flow diagrams, they dont make a whole lot of sense. I can make out some things but id need someone that knows what they are looking at beside me to tell me 100%
 

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WATCH OUT for the screwy wiring advice here.
"Drivers Found" is just another Vortexer who can make a mistake like anyone.

That mystery wire from the KNOCK BOX to the STARTER 50 (Solenoid 12V during cranking) ncbrock has an issue with, supposedly from T10 on the Knock Box. Obviously there is no reason at all to send 12V into T10 of the Knock Box during starting.

T10 in fact is a R/Y wire added to ground the 4-pin CIS-E fuel pump relay and turn it on. So add the new wire or use the old relay.

Fuse 17 was reserved for the Knock Box power supply requiring another new wire.
 

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I'm working on a carb + knock box + ICM setup right now. I took my knock box apart to sort out this T10 thing.

My box is part number 811 907 397 E. The one with yellow lettering. Cannot guarantee the internals are the same for the other one(s).

T10 is connected directly to the collector of an NPN transistor, a BC337 to be exact. The emitter is connected directly to ground (T3).

This make sense, as MacGruber stated, it drives the low side of the fuel pump relay. I can only assume this is done so the fuel pump does not run all the time when the ignition is on and the engine is not turning. The knock box does this rather than the fuel computer as it's the one with the RPM input.

Time for some assumptions and a hypothesis.

Assuming I am correct in that the fuel pump will be shut off in the absence of RPM. I also don't think these cars prime the fuel system, otherwise there would be no point to the fuel accumulator, the knock box could issue a prime pulse, I'm not sure. This means when you turn the ignition on you will see 12V on T10 through the fuel pump relay coil while the pump is off. While cranking you will still see 12V while the knock box gets synced to the RPM signal, and then probably a bit of a delay in your meter. Once RPM is detected and the transistor is turned on current will flow though the relay and you will then see 0V on T10 just about at the same time you stop cranking. This makes it look like T10 is receiving power during cranking and I bet the origin of the powered T10 myth.

What does this mean for people who connect T10 to 12V? You killed the transistor and it doesn't do anything anymore. Which is fine because if you weren't using T10 as originally wired you don't need it anyways.

Unless of course there are different knock boxes that do different things with T10. In which case this only applies to the E variant. Everyone send me your knock boxes so I can take them apart!
 

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Take a look at the Bentley schematic for Engine Controls - 16-valve Scirocco and notice the +12v wire running FROM the starter (called 15a) - actually 2 wires,
one to the Cold Start Valve.
one to the ECU T24 - a cranking signal.

No starter wire leads to the knock box.

How does the fuel pump prime? My CIS car primes via the large fuel pump relay receiving ignition switch +12v. If the pressure is already high enough the fuel pump doesn't do anything.

 

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How does the fuel pump prime?
IIRC the knock box primes the pump at power on for a second, then it shuts the pump off until until the engine starts turning (hall input).


If the pressure is already high enough the fuel pump doesn't do anything.
strange, there is no fuel pressure switch or sensor so I"d say the fuel pump priming is not pressure related..
 

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Take a look at the Bentley schematic for Engine Controls - 16-valve Scirocco and notice the +12v wire running FROM the starter (called 15a) - actually 2 wires,
one to the Cold Start Valve.
one to the ECU T24 - a cranking signal.
The scheamtic I am going of shows a "cranking" wire to T24 on the fuel computer as well. Not sure why the CIS computer cares though. On an electronic injection system it would go into a different cranking map. On CIS the cold start colenoid is driven directly from off the starter. Must do some other stuff durring cranking. Regardless I think we both agree T10 does not go the the starter.

IIRC the knock box primes the pump at power on for a second, then it shuts the pump off until until the engine starts turning (hall input).
strange, there is no fuel pressure switch or sensor so I"d say the fuel pump priming is not pressure related..
That's exactly what I was going to ask/say. Even if there was a pressure switch, the knock box controls the fuel pump and it definately does not have a pressure switch input.
 
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