Caddy 9KVF 2002@155k km intermittent GP-light, relay 109 seems OK

I bought this car used about two months ago. The seller told me it would loose power on inclines. It sure did on the test-run. The oil-buzzer would also sometimes blare, dependent on the position of the gas pedal, and the tachometer was a little shaky. (He also told me it had a servo-leak, but that seems unrelated). I took a gander at the fuel filter, which looked quite old, with a long bubble in the hose; got it cheap, hoped for an easy fix, and put a new filter with new O-rings in. It ran fine on inclines for close to two months after that. Two other problems persisted: The oil-buzzer blaring (no light) seemed to depend on the weather. The shaky tach was always shaky. I read into it, and suspected the crankshaft position sensor, as it controls the tachometer, and people had reported oil-buzzer-blaring in relation to the CPS in forums. I measured the resistance of the CPS at 1140 Ohms, with a cold engine, on two occasions. A new one is supposed to be around 900. Before I got to changing the CPS, however (it was bolted with a strange 12-pointy bolt, for which I had no fitting tool), the story took another turn.

Three days ago, it suddenly would not start anymore. The glow-plug light was not coming on. The starter turned the engine at good speed, but it would not catch at all. I put in another battery, but no change. Tried to bump-start it, but to no avail. "17656 - Start of injection timing regulation - control deviation", was the only code. Perhaps that can be ascribed to the earlier bump-start. Nothing about the CPS.

So, I started reading, and found the Relay 109-DIY on here. It fit my symptoms exactly. I pulled the 109 and energized on my desk at room temperature. It seemed to close just fine. I heated it up with a hair-dryer until it was too hot to touch. It still closed just fine, and the measured continuity was good when closed. I put it back in the car, without the cap on, and it still visually closed just fine, but still with no GP-light (see video of it at https://youtu.be/bhpdmotBJfA). I looked for fuse 32, but I only have 22 fuses in the main box, and three more atop the battery.




I proceeded to clean all the connections around the battery, and inside the battery clamps. Everything atop the battery, below the battery, and also the connector to the fuel solenoid. It all looked good and shiny. There was also good voltage on every fuse atop the battery. This didn't help any.
I took the covers around the ignition switch off, and wiggled the connections there. They all looked good. No difference in starting behavior.

Then, I proceeded towards the ECU. Main ECU power from relay 109 is supposed to arrive at connection 1 and 2. There was no numbering, so I measured voltage and continuity at the four largest connectors, and the two smallest ones adjacent to them. With the ignition on, there was no voltage, but continuity with the negative terminal on the battery with all of these


I tried to pull the ECU for further inspection, but its fastened to the chassis at its back somehow:


So, after reconnecting the ECU, I tried starting again. No GP-light at first, but then, it came on after about ten seconds. I turned it off and tried again - the GP-light came on after about two seconds. I repeated: The GP-light came on almost instantly. Then I waited two minutes, and tried again: Seven seconds before the GP-light came on. Then quicker after that.

BTW, Imgur-picture-uploads do not work? This is my first post.

Edit: I went out after a few hours, and tried it again. I put my finger on the 109 and switched the ignition on. I felt one immediate vibration just as I turned, then a strong one, about ten seconds later, as the GP-light came on, and then a weaker one a few seconds later. Then, nothing more.

So, today, I twisted the key and waited for the GP-light. This time it took four minutes. The longer it goes in between each start, the longer for the GP-light to come on. The first time the GP-light went on today, it flickered once, with a loudish click from the engine bay.

The think the IP-light was steady after that, but I'm not sure. The faster the GP-light came on, the more clicking. I heard this same thing a few days earlier. Here's a video of it:

https://youtu.be/ctvCy9toEqw

I ended up replacing the 109-relay, which seems to have taken care of the engine problem. I've been driving it for more than two hours, with no incident thus far. The GP-light delay is also gone.

So, the car died en route again. Went off like switched off, after driving about 40 km. As I was losing speed, I tried to restart. It would start, but died like switched off after five seconds, or so, and I had to take it to the side of the road. Not too far from home, luckily.

It was the 109-relay again. I had gotten another black, perhaps 1st gen., from a junk-yard, to fix it the first time. It ended up lasting three months. From now on, I'm keeping one spare grey in the car.