On my 1998, ~100K mile, 2.0L DTH Vectra diesel (not a stranger to this group) a new puzzling warning light scenario has arisen recently.
With the engine warm and lightly loaded or even on the overrun at, for example 40 mph in 4th gear perhaps at 2000RPM, the MIL sometimes comes on. Revving-up or taking the foot off the throttle has no effect on the light but a gentle dab on the footbrake immediately clears it.
What does the footbrake have in the way of links to the computer? No other light comes on. No ABS warning lights. There is plenty of brake fluid in the reservoir and plenty of oil in the engine. I recently replaced the poor condition vacuum pump and there are no diaphragm leaks on the EGR or the manifold valve actuator. I have a gauge connected to the vacuum circuit and that is no longer 'iffy' now I have changed the pump. I changed the mass airflow meter about 1 year ago and the car shows no problems under heavy acceleration
It is very inconvenient to get the local dealer to read my vehicle with the Tech2 computer - even for money. Has anyone come out with an adaptor which will link the car to a computer for the later Vectra connector - not the old count the blinks method for the early vehicles?
Perhaps you have experience of this strange symptom or have a knowledgable line of investigation? Please share it with me.
As always your combined wisdom is highly valued.
Many thanks in advance.
Tony.