2G NO TACH SIGNAL 2G

[lololobster]

Hey guys, ive done alot of reading and testing and im really struggling with this, the runs and drives and on ECMlink it has rpm from the CAS, i did a manual swap to this chassis and already spliced the AT connector for the starter, i have tried

-2 ptus
-2 clusters
- wiggle test
and finally i did a continuity test from
-pin 4 on PTU to pin 58 on ecu - .2 ohm
-pin 4 on ptu to pin 24 on connector c-05 on cluster harness connector - .2 ohm

any suggestions would be great, i feel like im missing something in the manual swap but havent read about anything like this, TIA

 

[luv2rallye]

Did you ground ECU pin 91 for a MT?
Also I assume you checked if PTU pin 6 has +12V with key on.

 

[lololobster]

Did you ground ECU pin 91 for a MT?
Also I assume you checked if PTU pin 6 has +12V with key on.

pin 6 has 12v

pin 91 is the neutral position switch. I believe that's the wire I spliced at the AT connector in the engine bay. When I check against battery ground I get 80 ohms. When I tried to start it with it grounded, the car wouldn't start and the wire got quite hot, normally it will start.

 

[steve]

Grounding pin 91 that way would be a bad idea since the AT wiring harness also has it connected to the power input to the Starter Relay coil (which comes from either the Ignition Switch or the Theft-Alarm circuit). The other side of that relay coil is connected to ground via the P/N Switch but grounding it via the AT harness would create a short to ground of the Ignition Switch ST position and leave the AT Starter Relay open. (Didn't this change between years on 2G for the MT and AT to use the same relay?) On MT cars the relay is NC and powering it via the CSS opens the contacts, on AT cars the relay is NO and the P/N switch powers it and switches it closed.

In my quick check this morning I don't see a connection to the ECU for the P/N Switch like on the 1G. It looks like pin 91 is NA on a 2G MT car.

The Output from the PTU on pin 4 also runs to the Pin 46 on the AT TCU and you need to make sure nothing is pulling it to ground.

 

[lololobster]

Grounding pin 91 that way would be a bad idea since the AT wiring harness also has it connected to the power input to the Starter Relay coil (which comes from either the Ignition Switch or the Theft-Alarm circuit). The other side of that relay coil is connected to ground via the P/N Switch but grounding it via the AT harness would create a short to ground of the Ignition Switch ST position and leave the AT Starter Relay open. (Didn't this change between years on 2G for the MT and AT to use the same relay?) On MT cars the relay is NC and powering it via the CSS opens the contacts, on AT cars the relay is NO and the P/N switch powers it and switches it closed.

In my quick check this morning I don't see a connection to the ECU for the P/N Switch like on the 1G. It looks like pin 91 is NA on a 2G MT car.

The Output from the PTU on pin 4 also runs to the Pin 46 on the AT TCU and you need to make sure nothing is pulling it to ground.

I have the tcu disconnected, could this cause that issues? Edit: i plugged the tcu in and nothing happened

Also pin 91 is there on the harness, do you just mean it doesnt have the same function as a1g?

 

[steve]

I have the tcu disconnected, could this cause that issues? Edit: i plugged the tcu in and nothing happened

No, what could make a difference is whatever you did to switch from automatic to manual. Since the tach should have worked when it was an auto it should now but it's not. I've only done the AT to MT swap on a 3S and there was a lot of conflicting information out for that.

Also pin 91 is there on the harness, do you just mean it doesnt have the same function as a1g?

No I just missed the page where it shows that on a 2G MT car pin 91 is connected only to ground. So it is like a 1G in that it's connected to battery voltage on an AT and ground on a MT. (But not connected to anything else).

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[lololobster]

I have the tcu disconnected, could this cause that issues?

Also pin 91 is there on the harness, do you just mean it doesnt have the same function as a1g?

No, what could make a difference is whatever you did to switch from automatic to manual. Since the tach should have worked when it was an auto it should now but it's not. I've only done the AT to MT swap on a 3S and there was a lot of conflicting information out for that.

-I cut the hole for the master
-Swapped cables
-And did the neutral switch bypass on the AT harness connector

From what ive read this is all i need to do, im not sure if it worked before I swapped it, i bought the car as a shell unfortunately

 

[luv2rallye]

I didn't realize you still have the AT wire harness where pin 91 goes to the key Start position (+12v on start). Then Steve is correct - do not connect this pin to ground or you will have a direct short when key is in Start position.

Just a thought but perhaps try unplugging the filter noise capacitor to see effect (in case it's bad) since that is connected to PTU pin 6.

 

[lololobster]

thanks for the reply, i dont have one installed currently

the problem persists

 

[luv2rallye]

Does your tach gauge twitch at all or just completely dead?
And you said the TCU is unplugged correct?

If you have an analog (needle) voltmeter try measuring PTU pin 4 on 15v DC scale (also small AC scale) while cranking/running to see if get anything at all. {a digital meter may not read anything on just cranking but it may read something if running}. If PTU tacho is working you should have a value somewhere between 0 and 12v - not 0 or 12v. The signal should be a pulse train and so the volt meter should read an average of something between 0 and 12v (perhaps twitching if just cranking).

 

[lololobster]

Does your tach gauge twitch at all or just completely dead?
And you said the TCU is unplugged correct?

If you have an analog (needle) voltmeter try measuring PTU pin 4 on 15v DC scale (also small AC scale) while cranking/running to see if get anything at all. {a digital meter may not read anything on just cranking but it may read something if running}. If PTU tacho is working you should have a value somewhere between 0 and 12v - not 0 or 12v. The signal should be a pulse train and so the volt meter should read an average of something between 0 and 12v (perhaps twitching if just cranking).

the tach never moves cranking or running completely dead
the TCU was unplugged, i just plugged it in after someone brought it up and no change

i can see if someone i know has an analog meter but i only have digital unfortunately

 

[luv2rallye]

Well you can try the digital while engine is running to see what you get (try both small DC and AC scales).

You are running the stock PTU and coil for ignition correct?

 

[lololobster]

Well you can try the digital while engine is running to see what you get (try both small DC and AC scales).

You are running the stock PTU and coil for ignition correct?

correct, ive tried a couple of ptus

 

[luv2rallye]

Did you say you're not sure if the tach worked before or when you got this chassis or before you did the AT to MT conversion?
But the engine runs ok on all cylinders?
Another thing I thought of is to check all the connectors to make sure those pins are locked in place and not bent. If not locked in place they get pushed back when connected.

 

[lololobster]

Did you say you're not sure if the tach worked before or when you got this chassis or before you did the AT to MT conversion?
But the engine runs ok on all cylinders?
Another thing I thought of is to check all the connectors to make sure those pins are locked in place and not bent. If not locked in place they get pushed back when connected.

i havent seen it work on this chassis ever, i bought the car as a shell 2 years ago, did a AT->MT swap about a year ago still no engine, and about a month ago i got first start and i noticed this issue so ive never seen a tach work on this car.

it runs on all cylinders however im having a tuning issue where my injectors have to be turned up about 20% more than calulated global fuel %. i have no idea if its related to this issue, its another perisistant problem that i cannot seem to fix after consistant diag and new parts. the only weird symptom ive noticed is a noid light juuust barely makes light when i put and injector pulse to it from manually spinning CAS, ill link that thread i started below, maybe you can connect a dot that i cant, im getting a little dishearted with thses issues

ECMlink - Global fuel wayyy off

hello everyone, ive hit another snag trying to tune my first car, when trying to set my fuel settings it seems i need to set the global fuel to almost half of what is required in order for the car to run2.0 built 6 bolt jmf intake with o-rings 43 psi at AFPR (fuel pump always on car not...

www.dsmtuners.com

i have replaced the PTU connector with a known good unit from another chassis i have

 

[luv2rallye]

Well maybe also try putting that 0.20uF - 0.49uF, 50V minimum noise capacitor back on the coil pin 3. I don't see how its absence would kill the tach but ya never know. You're sure someone didn't put one on in a different physical place so you didn't see it (and it went bad)?

 

[lololobster]

Well maybe also try putting that 0.20uF - 0.49uF, 50V minimum noise capacitor back on the coil pin 3. I don't see how its absence would kill the tach but ya never know. You're sure someone didn't put one on in a different physical place so you didn't see it (and it went bad)?

im sure, ill see if we have a noise capacitor at the shop to throw in to try, thanks for the suggestion!

 

[luv2rallye]

This engine is a 2g 4g63 turbo correct? What year?
Or from your other post it may be a 1g 6 bolt swap turbo? What year engine and body wire harness?

At this point before proceeding any further, you may need to verify if you REALLY ARE getting a signal out of the actual PTU pin 4 (and the problem is just not the signal appearing at some other place that wire goes to). I suspect you probably are getting a signal. Unfortunately I've never seen that signal but it almost has to be a narrow pulse (either positive going or negative going) that occurs whenever a cylinder pair fires (1-4 or 2-3). It's going to be so narrow that you may need an oscilloscope (which is why I doubt you'll see it with either a digital voltmeter or noid light - but you may get lucky with an analog meter seeing the needle slightly twitch although being so narrow you may not see it there either). If you have a frequency setting (hz or freq) on your digital meter that may read it if the pulse is wide enough.

The real problem is probably downwind where PTU pin 4 goes (like a partial short or broken wire/connection). Of course to check pin 4 output by itself you'd have to cut the wire so it doesn't go elsewhere anymore eliminating any possible interference (from what I suspect is the real problem). And of course you don't want to cut that wire if you don't have to.

Just thinking out loud here for ideas what I would do as this seems to be a real stickler problem. If possible, after verifying that the signal on pin 4 exists (without any load wires connected to it which may cause it to disappear, although this may be impractical to do), perhaps: disconnect the battery, unplug the PTU, and touch +12v through a small 50-100 ohm resistor in series (to limit current for safety should there be a short somewhere) onto PTU pin 4 of the connector side harness. Measure voltage there and then go around to all the places pin 4 is supposed to go (ECU pin 58, cluster C-05 pin 24, PTU B-62 pin 46 {do this even though the PTU is unplugged}) and see if the same voltage is at all those places. A partial short will show less voltage. An open or bad connection will show no voltage .

Another thing you might try with the battery connected and key to On (so cluster has power) is repeatedly touch (on, off, on, off, etc) that +12v through a resistor to unplugged PTU harness pin 4 to see if the tach gauge twitches. If not perhaps try repeatedly touching (on, off, on, off, etc) a ground to that pin to see if the tach gauge twitches. Of course if the tach gauge expects an entire train of pulses that may not work either - but ya never know, you might get a needle glitch. Perhaps try it on cluster C-05 pin 24 first.

 

[lololobster]

This engine is a 2g 4g63 turbo correct? What year?
Or from your other post it may be a 1g 6 bolt swap turbo? What year engine and body wire harness?

At this point before proceeding any further, you may need to verify if you REALLY ARE getting a signal out of the actual PTU pin 4 (and not some other place that wire goes to). I suspect you probably are getting a signal. Unfortunately I've never seen that signal but it almost has to be a narrow pulse (either positive going or negative going) that occurs whenever a cylinder pair fires (1-4 or 2-3). It's going to be so narrow that you may need an oscilloscope (which is why I doubt you'll see it with either a digital voltmeter or noid light - but you may get lucky with an analog meter seeing the needle slightly twitch although being so narrow you may not see it there either).

The real problem is probably downwind where PTU pin 4 goes (like a partial short or broken wire/connection). Of course to check pin 4 output by itself you'd have to cut the wire so it doesn't go elsewhere anymore eliminating any possible interference (from what I suspect is the real problem). And of course you don't want to cut that wire if you don't have to.

Just thinking out loud here for ideas what I would do as this seems to be a real stickler problem. If possible, after verifying that the signal on pin 4 exists (without any load wires connected to it which may cause it to disappear, although this may be impractical to do), perhaps: disconnect the battery, unplug the PTU, and touch +12v through a small 50-100 ohm resistor in series (to limit current for safety should there be a short somewhere) onto PTU pin 4 of the connector side harness. Measure voltage there and then go around to all the places pin 4 is supposed to go (ECU pin 58, cluster C-05 pin 24, PTU B-62 pin 46 {do this even though the PTU is unplugged}) and see if the same voltage is at all those places. A partial short will show less voltage. An open or bad connection will show no voltage .

Another thing you might try with the battery connected and key to On (so cluster has power) is repeatedly touch (on, off, on, off, etc) that +12v through a resistor to unplugged PTU harness pin 4 to see if the tach gauge twitches. If not perhaps try repeatedly touching (on, off, on, off, etc) a ground to that pin to see if the tach gauge twitches. Of course if the tach gauge expects an entire train of pulses that may not work either - but ya never know, you might get a needle glitch. Perhaps try it on cluster C-05 pin 24 first.

ok i will try all of this on the weekend and report back, thank you again for your help!

 

[luv2rallye]

Notice I added to my post #18: "If you have a frequency setting (hz or freq) on your digital meter, that may read it if the pulse is wide enough" in order to test for the signal on PTU pin 4.

 

[lololobster]

Notice I added to my post #18: "If you have a frequency setting (hz or freq) on your digital meter that may read it if the pulse is wide enough" in order to test for the signal on PTU pin

been a hectic weekend i havent been able to get out in the garage yet but my meter defineatley has a frequency setting

i also noticed i missed ytour question on the last post, it has a 6 bolt swap that i dont have any history on where it came from, the body and engine harness i believe are both from a 95 tsi as thats the shell they came with but i have no idea if theyre original

 

[lololobster]

ok im about to head out there to start some diag, when im tapping into pin4 with the frequency setting am i going in series on that snipped curcuit?

or negative lead -> battery ground and positive lead -> pin 4 wire (cut)

 

[luv2rallye]

Do: negative lead -> battery ground and positive lead -> pin 4 wire. Try without cutting pin 4 wire in case you don't need to. Cutting that wire is only necessary if there is a short downwind, in which case that would mislead you into thinking the PTU is not outputting the signal (on its side of the connector) where it may actually be outputting the signal (it's just being shorted so there's no reading). So only cut the wire if you can't tell if the PTU is actually outputting a signal so you can test it directly without anything else connected to pin 4.

 

[lololobster]

Ok here is the result of that, it seems to have a signal, not really sire the range im looking for tho

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[luv2rallye]

That fact that you're getting any reading at all tells me the PTU is outputting pulses. Don't worry about it jumping around. Your voltmeter expects a sine wave and it's far from it, so any reading, even changing values, says something is there while engine is running.