Nyx

Do you have access to a Bosch Hammer?

I believe the only speed sensor reference for RPM to be an output from the EZ69 (TD-16, BK/VI), then it passes to several control units and to the Bosch hammer test port. (Terminal 14, TD. Could also try Fritz’s suggestion of hz on a multimeter or oscilloscope here in the passenger footwell)


If your hammer sees a RPM in the pulse duty screen then your interface module has likely failed or your wiring. Check end-end with an ohm meter, devices disconnected at each end to prove the wiring is not faulty.

Would be very coincidental for the RPM/Pressure signal circuits to fail at the same time.

My annotations are just artifacts from previous troubleshooting, they can be ignored.

fritz k.

Ok, some considerations:

- the interface only works when it is plugged in, because otherwise the supply voltage and input signals are missing. This makes the measurements much more difficult.

- whether the car starts if the plugs of the pressure sensor and overboost switch are swapped depends on whether the latter can draw ground via the pressure sensor. I would have to try that out, though.

- @ NYX: if the TDC signal wasn't there, the car wouldn't start.

- since the tach worked fine before the clutch was changed, but no longer afterwards, it is very likely that the cause of the error is related to the job. It is very unlikely, however, that the interface passed away during the job.

A systematic diagnosis would now trace the signals from the origin to the end point, i.e. (boost pressure sensor - T30 - interface - tach) and (TDC sensor - EZ69 - T31- turbo control unit - T15 - interface - tach). That goes through the whole car and would be too complicated.

The two signals on the way to the speedometer have one thing in common (except the interface) , and that is the ground supply via ground point XXI and connector T30. I would therefore measure again to see whether there is a connection to ground on pin 8 of the 14-pin connector on the carrier plate on the left in the engine compartment.

The ground point XXI is on top of the engine housing, under the generator. There is also a connection to the starter there. If only the gearbox has been removed, the engine must be supported on the clutch side. Consider again whether the engine may have been lowered too far there and cables have been damaged there.


Cheers, Fritz

jd964t

Thanks to Nyx and Fritz for all the detailed info, great stuff.

Unfortunately I don't have a Bosch hammer but will test for tach signal with the multimeter on the diagnostic port. I've also read many posts where the tach signal has been tapped from the Bk/Gn wire on the 6-pin T15 connector under the left side seat. Is there merit in checking for a signal from both the TCU (Td signal #2 Bk/Vi) and T15 (Bk/Gn) connector?

I agree it seems too coincidental for both signals to fail at the same, unless the Control Unit died somehow when battery was reconnected?

Just for fun I'll swap the wires at boost sensor and overboost switch to see if it starts.

I too think error is related to clutch job but it was done on hoist with engine fully supported throughout, wasn't lowered. I also noted the shared ground point XXI but it's under the alternator and unlikely cables there were disturbed.

I will check for a connection to ground on pin 8 of the 14-pin connector on the carrier plate on the left in the engine compartment. I've probably looked at this area dozens of times but can't picture this connector - are there two of them?

Cheers

fritz k.

This can be helpful if you have a multimeter with an oscilloscope function. A square wave signal between 0.1 - 4.9 V should then be measured at T15.

Control units only die possibly if the poles are reversed when the battery is reconnected, which is almost impossible.

No, there is only one, which becomes visible when the plastic cover secured with two wing nuts is removed.

Fritz

jd964t

Thanks Fritz. After my previous post it occurred to me that I won’t be able to get a tach signal from the diagnostic port because the BK/VI wire for it also comes from the interface for the Control Unit. The other BK/VI wire from the interface goes to the tach and I had previously tapped that to get rpm for a data logger. It’s no longer recording rpm confirming loss of signal from the interface at least.

Cheers

jd964t

Managed to measure rpm at a consistent 45-50 Hz at idle (occasionally 55) by squeezing the multimeter onto pin #4 (BK/GN) of the 6-pin T15 connector under left side seat. This BK/GN wire then goes to the HKZ input of the Control Unit for OBC base (Interface Electronics) where for some reason I can't measure rpm (HKZ & Term 31).

I found two 14-pin connectors next to each other on the left in the engine compartment. One closest to intercooler with female top plug and the other with male top plug. With connector fully out measured female #8 at 0 ohms with key off & approx 15-16 ohms with ignition ON. With this connector out there is no power to starter, engine won't turn over.

On the other connector male pin #8 measured OL with key off & ignition on (as did female counterpart). With this connector out engine will turn over.

Could not test mixing boost pressure sender wire as overboost switch wire not long enough to reach so no chance of confusing them.

Are these the correct 14-pin connectors?

Cheers

Female top plug 14-pin connector (#8 for ground)


Male top plug 14-pin connector

Nyx

In my original post with the PDF's I noted inboard/outboard for those connectors. T30/T31 respectively. T15 is somewhere else, check the coordinates diagram in the wiring VOLIII.

Your system seems to be functioning okay since as Fritz said without the output from the EZ69 to your turbo'safety'relay the engine will not run.

Testing downstream at your pin 14 diagnostic power tells you if the interface relay is indeed outputting the signal to the other devices, which it is not by the sounds of it. The lack of the boost pressure would also suggest that. However tracing your wiring as you are now is a vital last step.

fritz k.

Hi,

- The two 14-pin connectors you found are T30 and T31. Both are connecting the engine wiring harness to the rest of the wiring harness.

- The plug that prevents the engine from starting when unplugged is T31. On the other (T30) continuity to ground should be measurable at pin 8. That is the case as far as I understand.

To move forward, I see the following options:

1. you create a way to measure the inputs and outputs directly on the attached interface (perhaps with a small auxiliary cable wrapped around the pin)

2. you get a known good interface to try out, perhaps from a fellow rennlister

3. You have the interface checked by a specialist service provider for the repair of control devices. This requires a precise description of the error and the circuit diagrams on sheets 5 and 6.

Cheers, Fritz

jd964t

[QUOTE=Nyx;19476338]In my original post with the PDF's I noted inboard/outboard for those connectors. T30/T31 respectively. T15 is somewhere else, check the coordinates diagram in the wiring VOLIII.

I have all the wiring diagrams and had also created a quick reference schematic for tach and boost but yours is better, thanks! The T15 connector is under the left side seat. It’s where I measured rpm (pin #4, Hz with multimeter) to confirm tach signal is going to the Control Unit base.





I tested the 19-pin diagnostic port and was able to confirm switched power at pin #13 (Term 15) & pin #10 (ground). But there was no tach signal at pin #14 (TD) - was measuring 340 Hz plus.

Are the diagnostic port pins numbered the same as the standard 964, i.e. #12 top left, #18 bottom right?



@ Fritz

Re T30, pin #8 - confirm there is continuity to ground here. I think the Control Unit was unplugged the first time I wasn’t able to measure continuity.

I made some auxiliary wires with spade terminals and inserted into the interface base, no Control Unit (boost gauge stuck at 0.0 bar):

Term 15 & Term 31, supply voltage, 12.25v switched, 13.85v idle
Hz & Term 31, tach input, No Hz reading, 10.66v switched, 8.55v idle
P1 & Term 31, boost input, no ohms, no volts
TD & Term 31, tach output, no measurement spade too big
LD & Term 31, boost output, 0.40m ohms, 55m volts

Control Unit was then plugged back in (boost gauge stuck at 0.7 bar) with different auxiliary wires wrapped around pins:

Term 15 & Term 31, supply voltage, 12.25v switched, 13.85v idle
Hz & Term 31, tach input, No Hz reading, 10.66v switched, 8.55v idle
P1 & Term 31, boost input, 5.85k ohms at key off, on & idle
TD & Term 31, tach output, no Hz reading at idle, 102 ohms at idle, 0.3v at idle

Boost pressure sender at intercooler:
10.2 ohms key off
19 ohms ignition on
0.0 ohms at idle

So still unable to read rpm (Hz) at the interface base with multimeter probe or auxiliary wires. Thought this would be possible because it comes from T15 connector where rpm was measured.

And same result with Control Unit plugged in with wires wrapped around pins. Am able to get supply voltage measurement but no rpm. Assume no rpm at diagnostic port because no signal from interface - unless numbering is different from standard 964?

Cheers

fritz k.

This suggests that your interface does not receive a signal from T15 and therefore cannot output a TD signal.

Your guess is correct and the pin assignment on the OBD connector 964 / 964 turbo is identical.

I'm going to measure my car this weekend to see what the TD signal looks like. May take 1 to 2 days.

Fritz

fritz k.

I measured pin 14 of the OBD connector, i.e. the output interface. The speed signal at idle is like expected around 45 - 50 Hz.








On the oscilloscope it looks like shown in the vid (the scaling is not appropriate):


I didn't measure the input signals because that requires removing the seat or the interface.

The resistance at the boost pressure sensor is 15 ohms without and 17 ohms with the ignition on.





Maybe it will help a little.

Fritz

Owjdbsb

Mine has a delay in the reading

Owjdbsb

Short of ringing out the wire from the sensor to the IP, take a pair of pliers and gently squeeze the female spade connector on the wire together