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Wiring Harness Installation, Wire By Wire, Page 4 of 5 - ET-100L

ET-100I - Grounding, Tools, and Resistances
ET-100J - Primary Lighting Circuits
ET-100K - 1500 Type turn signals and brake lights
ET-100L - 1600 Type turn signals and brake lights
- (you are here)
ET-100M - Everything that is not lighting circuits

1600 Type turn signals and brake lights

The 1600 type turn signals and brake lights start out similar to the 1500 on the power supply side, like this:

Start with power to the Fuse Box. See here: ET-101 - Basic Circuits. You can connect both (2) white wires to output side of Ignition Switch. One goes to the ignition warning light, which is still not connected on the other side, so is of little concern whether that white is connected or not. The other white wire goes the Fuse Box.

Now see here: ET-101e - Switch On and Fused. Once connected at the Ignition Switch, turn on the IS, use test light to find white wire near FB that is hot, and connect that one wire only to terminal A3. (No need at this time to have power on white wires for ignition coil or fuel pump). Install the 17/35 fuse (or a regular 20-amp substitute fuse), switch on, use test light to verify power on the A4 terminals of the FB, then switch off.

From here the 1600 type turn signals and brake lights take a different form, because there are extra lamps at the rear and no turn signal relay required. See here: ET-101g - Switch On and Fused - 1600. There are two A4 terminals on the FB holding four green wires. Only two of these wires need to be connected now, one for the brake lights and one for turn signals.

Use a continuity tester to discover which green wire goes to the brake light switch, and connect that one first to the FB terminal A4. Leave petrol gauge, wiper motor, and flasher unit green wires disconnected from FB at this time. Turn on the IS, verify power on the green wire near the starter switch, and switch off. Use a snap connector to connect two green wires near the starter switch, switch on, verify power on the green wire near the brake switch, and switch off. Connect the green wire at the BS, switch on, verify power on the green wire terminal at the BS and open circuit on the other BS terminal. If no power here, investigate snap connector in green wire. Have a helper step gently on brake pedal, and verify power on both terminals of BS. If it requires heavy pedal pressure to operate BS, replace the switch. You can do that BS test at any time (now or later). Connect the green/purple wire at the BS. Install a jumper wire temporarily across the terminals of the BS (so you don't need a helper to hold the pedal down). Switch on, verify power on the green/purple wire at RR corner, and switch off.

Use a 4-way snap connector to connect three green/purple wires at RR corner. Switch on, verify power on the green/purple wires at RR and LR corners, and switch off. Connect green/purple inside the RR lamp, then switch on and verify operation (light up) of the RR brake light. Assuming the low light parking light was already working, this should be a cinch to give bright light for the brakes. If not, fix it before you go on. Switch off. Connect green/purple inside the LR lamp, then switch on and verify operation (light up) of the LR brake light. Assuming the low light parking light was already working, this should be a cinch to give bright light for the brakes here as well. If not, fix it immediately. Switch off. Remove jumper wire from BS, switch on, step gently on brake pedal to verify that both brake lamps light up, switch off. That's it, brake lights are done.

Use continuity tester to determine and connect the green wire from FB to the Flasher Unit. Connect three wires to the FU, green, light green, and green brown, to terminals B,P,L respectively. Switch on, verify power input to the FU on green wire (terminal B). Also verify power output from the FU on terminal L. This may show slightly dimmer light output for your test light because of internal resistance of a heater wire. You can also test this with an ohm meter on FU terminals B and L. The panel lamp terminal P should be open circuit at rest. Refer to another tech article for explanation of how the flasher unit works.

Then get behind the dash panel, switch on, verify power at the output end of the green brown wire near Turn Signal Switch in same manner as FU terminal L, then switch off. Connect the green/brown wire to the "F" terminal on the TS switch (F is for "flasher"). Switch on, operate the TS switch left and right, verify power on the output terminals of the switch, and switch off. Then connect the green/red and green/white wires to the R and L terminals respectively. (You should notice that the R and L terminal labels are swapped for the MGA, where R actuates the left signal and L actuates the right signal. This is entirely due to orientation of the switch manual actuator lever hanging down on the MGA where it extends upward on some other cars). Also connect the Light Green wire to the TS warning lamp (permanently connected with original parts), and plug the lamp into the dash socket. The lamp socket needs to be grounded on the dash panel, so either scrape off some paint or install a separate ground wire for this lamp mount.

In the engine bay near the starter switch, use a 4-way snap connector to connect three green/red wires, and another 4-way snap connector to connect thee green/white wires. Install a jumper on back of TS switch from F to R terminals), verify power on green/red wires at LF and LR corners, then switch off. Use a snap connector to connect two green/red wires at LF corner, switch on, verify operation of LF bright light. This should not flash with only one lamp connected to the flasher unit. If it doesn't work, fix it before going on. Switch off. Use a snap connector to connect two green/red wires at LR corner, switch on, verify power on green/red wire at LR corner, then switch off. Connect green/red wire inside the smaller (top) lamp fixture at LR, also verifying connection of black ground wire. Switch on, verify operation of LR bright light. This time it should flash because there are two lamps connected to the flasher unit (front and back). If no flashing, fix it before going on. Switch off.

Move the jumper wire back of TS switch from the R terminal to the L terminal (now connecting F to L). Verify power on green/white wires at RF and RR corners, then switch off. Use a snap connector to connect two green/white wires at RF corner, switch on, verify operation of RF bright light. This should not flash with only one lamp connected to the flasher unit. If it doesn't work, fix it before going on. Switch off. Use a snap connector to connect two green/white wires at RR corner, switch on, verify power on green/red wire at RR corner, then switch off. Connect green/white wire inside the smaller (top) lamp fixture at RR, also verifying connection of black ground wire. Switch on, verify operation of RR bright light. This time it should flash because there are two lamps connected to the flasher unit (front and back). If no flashing, fix it before going on. Switch off.

Remove jumper wire from TS switch. Switch on, operate TS switch to left TS position, and verify flashing operation of left side lamps front and rear. Operate TS switch to right TS position, and verify flashing operation of right side lamps front and rear. If anything doesn't work, figure it out and fix it. Switch off. That's it. All of the 1600 type lighting and brake lights and turn signals will be working. Rear parking lights work on the dimmer light of the lower lamp. Brake lights work on the bright light of the lower lamp. Rear turn signals work on the bright light of the upper lamp. Front parking lights work on the dimmer small bulb in the lower part of the lamp. Front turn signals work on the bright light of the larger bulb in center of the lamp.

Now we can get on to the final few items that are not lighting circuits. (And you thought I was done? Ha!)

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