Re: Looking for repair of broken TL ride
Posted by HH56 On 2019/1/26 12:40:24
The purpose of going thru the brake switch is to prevent operation of the TL when brakes are applied. Whether stopping the action during braking is that important I don't know. Packard glossed over the switch in their SAE description paper just saying the brake switch was to prevent operation during braking but no specific reason why. I believe I remember reading in another publication it was because when coming to a stop, inertia may make the level want to change. If the front is down when the car is stopped after braking the compensator would want to level and there is no need if the car is going to level out on its own upon acceleration. Having the compensator active when brakes are applied would only cause the compensator to work again to relevel a second time. It sounds like the mechanic has defeated the switch entirely by running voltage directly to the green wire and TL circuit.
Normally on a 56, 12v power for the TL comes from the battery terminal connection at the starter solenoid via a red wire thru a 30 amp fuse to the buss bar at the TL solenoids. That fuse is overall TL power and is high amp for the motor power. On a 56, from that same fuse and buss bar connection point, power is taken and run back out thru a separate 7 1/2 amp fuse via a pink or purple wire directly to the common terminal of the brake switch to feed the TL control switch internals and the brake lights. In theory with that arrangement if there was a problem with brake lights & wiring or control switch & wiring the 7 1/2 amp fuse only would blow but in actuality they would probably both go. The downside in the 56 circuit is if there is a problem with the compensator motor and the 30 amp fuse blows the brake lights also go. Both fuses use inline holders located next to the solenoids on the left inner fender panel.
When brakes are relaxed 12v from the fuses is fed from the common to the brake switch normally closed terminal and out the green wire and ultimately the TL switch. When brakes are applied the switch changes and voltage is cut from the light green TL control circuit and goes directly via the normally open switch terminal to the dark green wire and brake light bulbs. The light green wire only provides power to the TL control switch and not the brake lights. Not sure which diagram your mechanic is looking at to conclude the light green wire is providing power to the brake lights.
For the voltage to be only 5v at the brake switch, assuming nothing has been changed from the stock power source or added and is somehow pulling the voltage down, it sounds as if one of the fuse holders or a wire connection has some poor contact issues. Old fuses can age and get a high resistance and contacts can oxidize in the holders. Possibly there is a miswire at the brake switch or a bad connection at that 3 position plug if it is still in use with the VW switch. Some have had issues with longevity when using the VW 3 terminal switch so most have now gone to the commonly available 2 terminal switch and relay conversion if the original switch needs replacing. If the car has had a manual operation switch added and that was done improperly it could also be causing an issue.
55s use a different fuse and component layout so TL (and brake lites) get power from two fuses from independent sources. A problem with the compensator motor doesn't disable brake lights on 55s but other than that the electrical operation is the same.
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Normally on a 56, 12v power for the TL comes from the battery terminal connection at the starter solenoid via a red wire thru a 30 amp fuse to the buss bar at the TL solenoids. That fuse is overall TL power and is high amp for the motor power. On a 56, from that same fuse and buss bar connection point, power is taken and run back out thru a separate 7 1/2 amp fuse via a pink or purple wire directly to the common terminal of the brake switch to feed the TL control switch internals and the brake lights. In theory with that arrangement if there was a problem with brake lights & wiring or control switch & wiring the 7 1/2 amp fuse only would blow but in actuality they would probably both go. The downside in the 56 circuit is if there is a problem with the compensator motor and the 30 amp fuse blows the brake lights also go. Both fuses use inline holders located next to the solenoids on the left inner fender panel.
When brakes are relaxed 12v from the fuses is fed from the common to the brake switch normally closed terminal and out the green wire and ultimately the TL switch. When brakes are applied the switch changes and voltage is cut from the light green TL control circuit and goes directly via the normally open switch terminal to the dark green wire and brake light bulbs. The light green wire only provides power to the TL control switch and not the brake lights. Not sure which diagram your mechanic is looking at to conclude the light green wire is providing power to the brake lights.
For the voltage to be only 5v at the brake switch, assuming nothing has been changed from the stock power source or added and is somehow pulling the voltage down, it sounds as if one of the fuse holders or a wire connection has some poor contact issues. Old fuses can age and get a high resistance and contacts can oxidize in the holders. Possibly there is a miswire at the brake switch or a bad connection at that 3 position plug if it is still in use with the VW switch. Some have had issues with longevity when using the VW 3 terminal switch so most have now gone to the commonly available 2 terminal switch and relay conversion if the original switch needs replacing. If the car has had a manual operation switch added and that was done improperly it could also be causing an issue.
55s use a different fuse and component layout so TL (and brake lites) get power from two fuses from independent sources. A problem with the compensator motor doesn't disable brake lights on 55s but other than that the electrical operation is the same.
Attach file:
(130.42 KB)
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