"ehsjr" wrote in message ...
On 9/22/2013 8:20 PM, Guv Bob wrote:
"ehsjr" wrote in message ...
On 9/22/2013 11:43 AM, Guv Bob wrote:
"Guv Bob" wrote in message m...
"ehsjr" wrote in message ...
On 9/21/2013 7:46 PM, Guv Bob wrote:
The +12 from the LED connects to this component unfamiliar to me.

In your earlier post you talked about the check engine _bulb_

Now you mention an LED. Is the check engine light an LED rather
than a bulb? It makes a big difference.

Ed

Correction....
GE LIGHTING 74 LIGHT BULB
14 volts; 1 watt



Ok. That means the bulb draws about 71 mA and provides
about 200 ohms resistance when hot. If the schematic is
correct, then you can use a 22 ohm 1 watt resistor between
the transistor's collector and the bulb to replace the
existing resistor, if it's bad.

Ed

Thanks Ed. My problem is finding the transistor. The circuit connects from pin 64 of the connector to CM104. I'm lost from there. There's no way to know where it leads from there, and no schematic showing where the base signal comes from.

I'll keep looking for a schematic. In the meantime, I'll take the suggestion to his the junk yards.



Groan. In fact, double groan. Tracing the thing out on the ECU,
if that is possible, still might not yield the fix, because the
transistor/resistor might be good. If you could trace it to the
transistor/resistor, you could use just about any NPN transistor
to replace it and add the 22 ohm resistor, but that still might
not fix the problem. And, who's to say something else won't become
defective in the disassembly/troubleshooting/repair/reassembly
activity. Grumble.

Ed

Ditto to that, Ed. I'm not one to give up but once I get a working ECU, I'll tear into this one and keep looking. This particular version was known to have used faulty capacitors. This is the 3rd time in 10 years I have traced the problem to the board. Unfortunately for me, there are no more caps to replace. Lots of corrosion though where I can't get to it without taking a chance on ruining something.

My comment on smog checks.... this car is WAY underneath the pollution emissions and runs like a top. Two things prevented it passing -- the check engine light and the mechanic couldn't find the timing mark. LOL!! I couldn't find it either. Had to keep tapping the engine and marking the pulley feeling every stinking 1/2 inch of the edge. Tried smearing it with oil and every other trick. Looking for it with a bright timing light wouldn't even work. Finally found it and marked it with paint, and yes the timing was exactly right where it should have been.

As much as I would like to keep it, once it's up and smogged, it's going to El Cheapo paint shop for a shiny bright red coat, adding the gaudiest wheel covers I can find, a license cover that says "BABE MAGNET" and For Sale sign and parking it right in front of the high school.