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
me.
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.
suggestion to his the junk yards.
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.
me.
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.
suggestion to his the junk yards.
May be making some progress again.....
this)....
it? It is labeled CM104. Can't get a clear view for a photo. Rough sketch....
can't get to. No markings on it that I can see. There are 7 of these on the board, all packed close together under a metal piece which is not practical to remove.
there.
The bulb and all circuits external to the ECU board are fine. The board is also good between the 12VDC into the board from the bulb and ground. I suspect the trouble is the transistor or associated capacitor, but the board has been worked on before and the markings on these parts are no longer readable.
type of circuit could guess at a possible replacement for the transistor and capacitor.
buying a new ECU - several hundred $$. So I'd like to try a few things that mght have a chance of working before doing that.
resistor on the board, but no info as to what the parts are. Also, can't find what is connected to the base. I can swap out the parts from the component side of the board OK, but can't trace the leads or it would likely damage something else on the baord -- due to the condition of the board. I just need the car to pass smog so I can continue restoring the car, but dont want to put a lot of money into anything until I'm sure the car is worth it.
send a few $$ for a copy. I need to troubleshoot the check engine light circuit and have traced it to the ECU circuit board.
entering/leaving the board, one cap per signal to a common ground pin. It may however be the cause of your problem though, as I see from your pics that someone has replaced the electrolytic capacitors which are renowned for leaking. They can cause much grief initially and again some years later. The electrolyte from the leaking caps can eat away the copper tracks if it hasn't been cleaned effectively. From the pics you have uploaded it looks like TR3 in the gif image wyu is the CEL lamp driver. The large flat pad should lead to a small value resistor, possibly 3.3 ohms (colour bands orange orange gold). Check for continuity between ECU terminal 64 and what should be the closest end of that low ohm resistor. If you have continuity then it might be a real component failure not just a track eaten away. I will upload a pic of an ecu I have here but the component designation numbers are different. If you can upload a downwards looking pic that covers both sides of the thick film hybrid IC101 (E518 on back) that would help.
no success. It's all just reverse engineering.
Here are some shots of a Galant ECU and my "Montero" which had been previously repaired - badly. Apologies in advance for the screwed up order.
The CEL control in both ECUs is functionally identical, only the names have been changed.
The close-ups of the CM106 location show the tracks corroded away by the remaining electrolyte.
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Thanks, Mark! That's a great help. Here are some new photos
This photo index might help you find the ones you want to see. All except #10 are in the 800K range.
Bob
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PS -- Checking - no continuity between pin 64 and any of TR3 contacts. Also, I checked 64 to R104 and all other transistors & resistors I could find in that part of the board and no continuity with any of them.
The trace from CM104 goes under CM105 which I can see is badly corroded. Looks like I will need to remove the power transistor heat sink, clean that up and just go one step at a time.
Stay tuned! =O)
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