Back to working on bike after 4 yr break

[1strauss]

What is the voltage test?

[dbeardslee]

At the TCI, with both connectors in place and the ignition on, but not running. On the big connector insert a dmm probe from the back of the connector - grey to ground (12v), white/red to ground (12v), black/white to ground (6v), orange to ground (12v), and red/white to ground (12v).

[1strauss]

OK, I'll try that when I get back to the shop

[1strauss]

At the TCI, with both connectors in place and the ignition on, but not running. On the big connector insert a dmm probe from the back of the connector - grey to ground (12v), white/red to ground (12v), black/white to ground (6v), orange to ground (12v), and red/white to ground (12v).

I did the voltage test. They are all 12v exept the black/white is 6v

[dbeardslee]

There's also a TCI quick test you can do with an analog mm, but unfortunately I can't find the procedure. TCI's tend to be pretty bulletproof, and I understand the tendency to look to the TCI for ignition problems, but it's rarely the TCI causing the problem.

You might check your pickup coil gaps - should be .7mm, or even a little closer. I'd also check continuity on the lines running from the TCI to the coils, and take a good look at your connectors. There are several behind the fuse block that often escape inspection, and you should probably make sure your engine grounds are in good shape.

I'll do a bit more digging and see if I can find the procedure for Randy Rago's TCI quick test. It's a real simple test... I just can't remember where to put the probes.

[1strauss]

Thanks, I appreciate the help. I'll check the pickup gaps but I'm thinking they are OK since I have used both pickups by switching wires to fire the 1/4 coil.

I'll check the wiring. I already checked continuity but that doesn't always mean the circuit is good and can work under a load so I may have missed something.

It's a simply system compared to the multiplexed electrical systems in today's vehicles... Sometimes I find myself overlooking the obvious. And I can't find the dlc to plug a scanner into this thing

[dbeardslee]

I found the procedure for Randy Rago's TCI quick test -

Using a voltmeter set on 12VDC, connect the positive meter lead to the Orange or Grey coil lead at the TCI. Connect the negative meter lead to the black (negative) lead at the TCI. Turn on the ignition. Voltage should come right up to about 10 - 11VDC. Crank the ignition and observe the meter. Look for a wide voltage swing during cranking. A strong swing indicates that the pickups and TCI are working OK and your trouble is between the TCI and the plugs. Possibly a bad ballast resistor, bad coil, bad plug cap or just corroded connections. Repeat this test for both Orange and Grey coil leads.

It doesn't say so specifically, but it seems to me like that test was supposed to be done with the spark plug wires disconnected. I also remember that the test only works with an analog multimeter.

[1strauss]

Thanks, Ill give it a shot. I did try something similar earlier....Not sure it was a valid test but this is what I did...

If the coils operate by basically opening and closing a circuit to cause field to collapse and this "opening and closing" is done by the TCI through the orange or gray wires...

With one end my test light clamped to battery positive and the other on the orange wire at the coil the light would pulse as the engine was cranked over. On the gray wire it would just glow dim and not pulse while cranking.

I also did the same thing with my fluke 85, not analog but there is a bar at the bottom that simulates what an analog needle would do. I got the same results, the orange would pulse and the gray would read about 8 volts.

If I'm thinking correctly this shows the TCI is bad since I have already swapped pick up coils by switching wiring and both can make whichever coil is connected to the orange wire spark.

[bikerphil]

If you open the TCI, sometimes you will find a broken solder joint at the plug terminal connector. If so, reheat, maybe add some solder, might be as simple as that.

[dbeardslee]

If I'm thinking correctly this shows the TCI is bad...

That is kind of what it sounds like. The good news is the 79's use the 2H7 TCI, and they're pretty easy to find. Or you could try resoldering as Phil suggested, but if that doesn't work, ebay is just a few mouse clicks away.

[1strauss]

Thanks guys, I checked that yesterday and resoldered a couple questionable joints. I ordered one from eBay for $45 so I won't lose the farm in case that isn't the problem.

[dbeardslee]

Last year around this time CatatonicBug's XS was giving him fits, and he finally narrowed it down to his 4RO TCI. This is a quote from when he fixed the problem -

Well, I may have solved my problem! Last night, in a bout of frustration, I desoldered the TCI from its housing, to take a look at the underside of the board. Today, I touched up a few pins, and paid special attention to all the through-the-board points that didn't have a component in them. When reassembling, one of the pickup coil pins actually LIFTED the race off the board, away from one of the through-the-board points! To clean it up, I used a tiny, .032" drill bit, spun between my fingers, and drilled out the path. Then, I used a single strand of copper wire, and soldered it on both sides of the board. Once I resoldered all the pins, I plugged everything back in, and it ran perfectly!

Reason I mention it is I was VERY impressed with his soldering ability, and general electrical know how. Might be worth touching base with him if you decide to go into your TCI. JAT

There's a bunch of them up on ebay, and it looks like they're running $70-$80 for the 2H7's - XS11 TCI's

[dbeardslee]

Thanks guys, I checked that yesterday and resoldered a couple questionable joints. I ordered one from eBay for $45 so I won't lose the farm in case that isn't the problem.

That sounds like an excellent price. Good job!

[1strauss]

I can't post pics from my phone right now but I did open up the box by cutting some plastic, rather than desoldered the joints(I don't have an iron I like right now) I visually inspected the board and components till my eyes quit working. Like you mentioned I have found bad joints on circuit boards before, wasn't so lucky this time

[1strauss]

It was 69.99 obo and he accepted 45. Supposed to be from running 1980 model