Wilsons Sandbox

I had a similar electrical gremlin attack my TC last summer. Symptom number 1: Engine did not stop when key turned off. Had to stall engine with clutch. Symptom number 2. Engine would start without turning on the key, but would not pull under load. Symptom number 3. Next time I turned off the key, horn sounded! Symptom number 4. Ignitiion (charging) warning lamp stopped working. Symptom number 4. Charging rate was 10 amps, regardless of state of battery charge. Then, without explanation, things fixed themselves, except that the warning lamp still does not operate. Car runs and charges normally now, and the key switch properly controls the ignition system. Can anyone provide insight into this situation? "B.A. Pockets Knipe" knipebs@hotmail.com> wrote: I think I fixed my MG-TC charging system problems. It was not the regulator or generator. It was a moron who disconnected the ground on regulator terminal E and disconnected the ignition warning light. I hope I fixed these two problems but now I cannot get the car to shut down when I turn off the ignition switch and remove the key (to stop the engine, I have to disconnect the battery). The white wires going to and leaving terminal IG on the regulator have been cut and replaced with "god only knows where they go" wires. There should be a mandatory hanging law against anyone who changes the wiring diagram with out marking the wires or leaving a new diagram. Questions: 1. Other than organization, is there any real difference between the two sides of the regulator (A-2 [via Ammeter side] vs. A4 & A3 [via Ignition side])? In other words, what is the difference between a "series windings" and a "shunt"? 2. I also cannot figure out why the previous owner wired the ammeter directly from generator terminal A2 to D without going through the IG terminal on the ignition switch (to make matters worst, there are already three wires attached to terminal IG and god only knows where these wires go). 3. Contrary to the wiring diagram, there appears to be two terminals associated with terminal IG on the back of the ignition switch. Am I correct? 4. Every terminal on my ignition switch is "hot" and/or grounded. It is possible that my ignition switch is broken. Does anyone know the schematic of a MG-TC Lucas Ignition/headlight switch? Does anyone know how to fault diagnose an ignition switch? I promise to be nice, work overtime to earn extra money, and completely rewire the car come October. For now, I just want to drive my MG-TC on sunny days. Is it too much to ask of a garage queen to just travel the beautiful back roads of America? Yahoo! Groups Links -Rick Waters --------------------------------- Post your free ad now! Yahoo! Canada Personals [Non-text portions of this message have been removed]

> Questions: > 1. Other than organization, is there any real difference between the > two sides of the regulator (A-2 [via Ammeter side] vs. A4 & A3 [via > Ignition side])? In other words, what is the difference between > a "series windings" and a "shunt"?

I think you are confused here. The shunt windings have nothing to do with A3 & A4. In fact A3 & A4 are totally independent of the regulator section as far as direct connections are concerned. A3 is fed by the ignition switch (IG terminal). Since the ignition coil is also connected to A3 the ignition switch also feeds the coil. A4 (both of them) are fed by A3 via a fuse. A4 feeds the wiper motor, fog lamp switch, brake lamp switch, petrol warning lamp and if you have one, the 30 MPH warning lamp. In the case of A1 it is fed by A (via series windings). The windings only are used so the regulator can sense current flowing and controls the dynamo but has no control over the A to A1 connection (as long as the windings are not burnt open). A1 then feeds the ignition switch (A terminal). You could actually connect terminals A on the ampmeter and A on the ignition switch and achieve the same connection but you would bypass the regulator and dynamo regulation would cease. A2 is just a fused connection to A1 and only feeds the horn. And lastly (and I am pretty sure I have this right but if I get this backwards I am sure someone will correct me) the series windings sense current flow and are part of what regulates the dynamo output. The shunt windings are used for the cut-out. If the dynamo is not putting out enough juice or not running at all as when car is shut off, then the cut-outs open to prevent the battery from draining back through the dynamo windings.

> 2. I also cannot figure out why the previous owner wired the ammeter > directly from generator terminal A2 to D without going through the IG > terminal on the ignition switch (to make matters worst, there are > already three wires attached to terminal IG and god only knows where > these wires go).

If A2 and D are connected via wire (hope I read your question right) then the dynamo is feeding A1 via the fuse, running through the series windings backwards to A and onto the ampmeter and battery. This would really confuse the regulator and I am surprised if there is any output at all.

> > 3. Contrary to the wiring diagram, there appears to be two terminals > associated with terminal IG on the back of the ignition switch. Am I > correct?

There should be a total of 4 terminals. The A is the input and IG is the output for the ignition system. H feeds the headlamps and T feeds the running lamps, and dash panel light switch. Again, A should be fed from the A1 terminal on the regulator and IG should be fed the A3 terminal on the regulator.

> 4. Every terminal on my ignition switch is "hot" and/or > grounded. > It is possible that my ignition switch is broken. Does anyone know > the schematic of a MG-TC Lucas Ignition/headlight switch? Does > anyone know how to fault diagnose an ignition switch?

See above but with everything turned off only one terminal should be hot and that would be "A". Good luck on getting the TC going. If I can assist or explain further, please ask. As you mentioned though, it looks like you are in for a few hours of tracing out wires butchered by PO. David Edgar, TC 5108 El Cajon, California