Power Probe vs. KL 30: Which is Best?

Hello everyone.

I work as a breakdown service technician. I had a case that presented me with a puzzle...

Alfa 156 GTA, wouldn't start after a short period of parking. The MIL (Malfunction Indicator Lamp) is flashing very rapidly, the starter motor is turning, but the engine isn't starting.
Alfa Vertragsgarage was already on site and determined: the error memory cannot be read.

I powered the main relay (KL87) using a Power Probe (a safety device that connects to the vehicle's battery and allows you to switch + or -), and the V6 engine started making noise again.
I found a problem, I'm building him a bridge at HR 30-87 and letting him drive it to the workshop!
However, whether I take the power supply from terminal KL 30 on the relay or directly from the positive terminal, it doesn't work.
"The car only runs when connected to the Power Probe. I've repeated this multiple times, and the behavior is 100% reproducible. Even if I start the car with the Power Probe and then connect pin 87 from the HR (presumably a relay) to either 30 or the positive terminal, the car shuts off."

Has anyone else experienced something similar?

Attached are the circuit diagram and a power probe.

Are you possibly applying pressure with the PowerProbe that isn't present in the bridge itself?
Then the pressure could cause a crack to form (e.g., in the circuit board of the relay).
These effects could be observed in the 109-type relays used in older TDIs.

Best regards,
Micha

... and in such cases, always check the ground connections as well, including whether the engine control unit has a proper ground connection.

"On a 1Z engine (which I believe was in an Audi 80), I once experienced the effect that if the engine control unit (ECU housing with the ground connection not screwed in), it would constantly restart, preventing the engine from running. When the ECU housing was properly screwed in, everything was fine. This shouldn't happen with a properly wired harness..."

Best regards, Rainer.

The control unit is grounding, therefore, bridge the 85 to ground .