I recently bought a 1990 Geo Tracker 4x4 5-Speed Manual. It has the stock 1.6L 8V Engine.
The owner tells me, "the computer is bad so the guy at the shop put in a toggle switch on the injector".
I cringed but it was a good deal so I bought it even though it's "hot wired".
I had a 1990 Sidekick before so I know a little about these. I drove it straight home and checked the CEL bulb. I pulled the dash and found the bulb had been removed. I robbed the bulb from the seat belt light and installed it into the CEL location. I turn the ignition ON and the CEL flashes 12s. Hum, the ECU thinks it's in diag mode... This is a 1990 Geo made in Canada, so there is no jumper in the fuse box. It does have the standard diag connector by the battery, but there was no jumper installed. I checked for shorts but I did not find any. It's a pretty clean tracker.
Anyway, the CEL just kept Flashing away 12, 12, 12. even when not in diag mode. Injector still would not fire, so I went ahead and flipped the hot wire and started it, but it doesn't stop flashing 12 unless the key is off.
Anyway I wanted to provide a quick history because I'm just curious if anyone had see that symptom before.
I just figured the ECU had bad caps, so I pulled the ECU and sure enough it is a Virgin and has the two bad Rubycons. I actually have a degree in electronics technology so I'm right at home. I grabbed my soldering iron and a solder sucker and removed the two bad caps. (C37 50v 100uF and C4 50v 47uF) Everything else looks pretty good.
I cleaned up all the leaked acid and I ordered some new high temp caps from mouser. I have some caps this size laying around, but I decided I wanted to use Nichicon 63v high temp caps.
The Diodes test good, and no blown traces. I'm hoping the transistors are good. They look good so I didn't test them. I figure it's quicker to put the two caps in and test the ECU, than removing the transistors to test them.
Anyway, while I'm waiting on the new caps, I have a question about the connections on the top traces to these caps. The bottom traces look great so there is no question there.
I'm about 90% sure where these traces connect because of the shape of the traces, but my problem is there are no copper pads there under the caps. I'll have no problem repairing these with a bit of wire, but I want to be 100% sure I'm making the correct connections. I'm guessing the acid eroded the copper pads away so there should be continuity to the nearest traces there.
If you have done this repair please check out the attached pictures. I marked the connections in with RED lines where I believe there should be continuity. There is also a little PCB damage between the two leads on C37 that I circled, but you can ignore that.
P.S. It's my first post on this forum, so sorry for being long winded...
Here are some pictures of the bad caps before I removed them. Just for reference.
The owner tells me, "the computer is bad so the guy at the shop put in a toggle switch on the injector".
I cringed but it was a good deal so I bought it even though it's "hot wired". I had a 1990 Sidekick before so I know a little about these. I drove it straight home and checked the CEL bulb. I pulled the dash and found the bulb had been removed. I robbed the bulb from the seat belt light and installed it into the CEL location. I turn the ignition ON and the CEL flashes 12s. Hum, the ECU thinks it's in diag mode... This is a 1990 Geo made in Canada, so there is no jumper in the fuse box. It does have the standard diag connector by the battery, but there was no jumper installed. I checked for shorts but I did not find any. It's a pretty clean tracker.
Anyway, the CEL just kept Flashing away 12, 12, 12. even when not in diag mode. Injector still would not fire, so I went ahead and flipped the hot wire and started it, but it doesn't stop flashing 12 unless the key is off.
Anyway I wanted to provide a quick history because I'm just curious if anyone had see that symptom before.
I just figured the ECU had bad caps, so I pulled the ECU and sure enough it is a Virgin and has the two bad Rubycons. I actually have a degree in electronics technology so I'm right at home. I grabbed my soldering iron and a solder sucker and removed the two bad caps. (C37 50v 100uF and C4 50v 47uF) Everything else looks pretty good.
I cleaned up all the leaked acid and I ordered some new high temp caps from mouser. I have some caps this size laying around, but I decided I wanted to use Nichicon 63v high temp caps.
The Diodes test good, and no blown traces. I'm hoping the transistors are good. They look good so I didn't test them. I figure it's quicker to put the two caps in and test the ECU, than removing the transistors to test them.
Anyway, while I'm waiting on the new caps, I have a question about the connections on the top traces to these caps. The bottom traces look great so there is no question there.
I'm about 90% sure where these traces connect because of the shape of the traces, but my problem is there are no copper pads there under the caps. I'll have no problem repairing these with a bit of wire, but I want to be 100% sure I'm making the correct connections. I'm guessing the acid eroded the copper pads away so there should be continuity to the nearest traces there.
If you have done this repair please check out the attached pictures. I marked the connections in with RED lines where I believe there should be continuity. There is also a little PCB damage between the two leads on C37 that I circled, but you can ignore that.
P.S. It's my first post on this forum, so sorry for being long winded...
Here are some pictures of the bad caps before I removed them. Just for reference.