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What with Craig's prompting, I thought I'd better try and get this sorted. Has anyone got the Honda engine charge warning light working on Rover instruments yet? I can't get it working from the hondata circuit (relevant pin not there on a UK spec engine loom), nor by tapping directly into the white/blue alternator wire which I think carries the signal to the multiplexer.
I've sketched out a circuit I think should work to provide the warning light. Any comments?
The Zener provides a max 12V reference to the non-inverting op-amp input. This means without charge, the potential divider voltage will be less than this and hence the lamp lights. As voltage rises with the alternator running, the inverting input will rise above 12V and turn off the charge light. The nice thing about the variable resistor is I could fine tune the voltage the lamp goes off. As the honda alternator seems to run at about 14V I could set this to 13 and so get early warning of any problems. I'll have a rummage in my parts tray and see if I've got the bits to knock this up and maybe try it at the weekend.
Richard
Yeah, problem is I tried tapping the B10 pin as hondata suggest, and also the wire right at the alternator - no success - the line stayed at 12v at all times (interestingly, it actually was 12 volts too, even when the battery was charging at 14V)
It's possible I damaged some of my alternator circuitry when I had it connected backwards initially... Charges fine, not found any other issues, but maybe damaged that part of the control circuit. I'll be interested to see if you get it working Craig.
Had it built and working fine outside the car on Sunday. Spent what seemed like the whole of this evening inverted in the footwell installing it and finally after much swearing it's in...and no longer working
I'd lost enthusiasm by then so fault finding can wait until tomorrow!
Had it built and working fine outside the car on Sunday. Spent what seemed like the whole of this evening inverted in the footwell installing it and finally after much swearing it's in...and no longer working
I'd lost enthusiasm by then so fault finding can wait until tomorrow!
That sounds familiar - head under the dash, with legs sticking out beyond the roll cage. Uncomfortable, and you can bet the next tool you need is ever so slightly beyond your reach.
On a different note, did your coolant displacement problem ever get solved? My coolant level didn't move (asides from expansion - it's at the same level now, as it was before the test) during my 140 miles to and from SVA, and I didn't drive the car gently. I'm using a current spec VAG coolant tank.
Got the light working a few days ago finally. Turned out the op-amp output wasn't pulling down sufficiently to extinguish the lamp, as the voltage difference is quite small. A pulldown resistor sorted that. Final circuit as so:
Reassuring to have that working - I can live with the alternator not charging, and gettting a flat battery, but if the belt snaps that means no water pump too.
