Hi all and HNY.
Due to circumstances etc I haven't really had chance to do anything re our miscreant 2004 1.6 Meriva A and it's semi-random non starting and crazy instruments.
So (and with the list of things I still will be checking still sitting here) could anyone shed any light on what I have been seeing with my OBD reader (OpCom) please.
Ok, simply symptom 1). after about 5 mins / 3 miles from cold the ignition light comes (and stays) on (but it's still charging ok) and typically the temp, revs and speedo will either die completely or start running intermittently. All other instruments are always fine.
At the same time the same values (coolant temp, engine revs and road speed) when seen on the ECU will be solid and constant.
So (trying to get my head round this) would I be at that point 'talking' to the logics of the ECU and it is determining these parameters are what it is experiencing and it *thinks* it is successfully outputting to (possibly amongst others) the instrument cluster?
So, if solid on the ECU, can we assume that any / all of the inputs that relate to those particular outputs (and I'm guessing they may be massaged by the ECU at some point ... taking pulses from an ABS sensor and converting that frequency into the equivalent MPH by knowing the rolling diameter / circumference of the road wheel etc) are ok?
So, the bit I'm not too sure about is how said signals are then fed to the instruments? I have pulled the plugs from the ECU and seen ~128 pins (between them) that obviously do something but are these particular outputs (and any other that would be pertinent between engine and instruments) fed individually or over some form of (CAN?) bus?
Now, the / first thought would be 'the classic (Corsa C) instrument connector problem but if after watching these instruments mainly off over a 50 mile trip, I can then immediately run the output tests on the instrument cluster and it has always been fine (I can turn on all the tell tails or move the temp, revs and speedo to any position I like and they stay there).
So, is there a different communication path from the OBD port that goes straight to the instruments (and hence why they work all the time) and a *different / intermittent* path from ECU to instruments and somewhere/how *that* path is now intermittent?
Given the semi-predictable nature of said intermittency (it's always fine from cold and rarely fine once warmed up etc), is this more likely to be a connection / electronics fault in the ECU than any issue with the loom or connectors etc?
What might put a slightly different emphasis on that last bit is that I think that pulling and pushing 'something' around the ECU connectors seems to have an impact on this instrument fault. I can't really tell if it's where the loom joins the plug, the plug in the socket (all pins clean and dry) or where the socket joins the PCB etc (if that could be moved by what I am doing on the outside).
I ask all the above because to check say the instrument cluster connector I'd have to do it in the road and it's not been particularly dry (or warm) out there of late. Plus I can actually use the thing as long as I don't try to restart it when it's tepid. [1]
Cheers, T i m
[1] I have noticed the last couple of times it hasn't started that it did actually fire up for about 1 second before dying. It has been suggested elsewhere that when it is in that condition (not one I typically try to get it into of course) to check the measuring blocks for the rpm and fuel relay on the ECU via OpCom.