Improving the Windscreen Wipers
The Wiper Motor
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Wiper wiring from the switch
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Following on from the problems identified with the window lift motor wiring I decided to look at the windscreen wiper motor.
The wipers have always managed to clear the screen on both slow and high speed but they seemed only just to manage the task and would struggle unless the screen was very wet.
First I decided to remove the multiway socket from the motor socket but found that it was stuck fast. Eventually I freed it but in the process pulled one of the pins out of the plug and self parking switch. I found that the pins and socket were covered in rust, due no doubt to rain water and hardly the best conductor of electricity. So the first job was to replace both the self parking/switch and the mating socket. There are many suspect replacement items on the market but I found the ones supplied by Car Builder Solutions were identical to the original Lucas items. As an amusing aside and to illustrate the possible problems with using pattern replacement wiper motor parts have a look at: Wiper Problems
Fitting the self parking switch onto the motor frame is a bit fiddly and it is worth checking before reinstalling the wiper motor that the self parking switch actually works as if the switch is not located accurately the cam on the gear wheel either misses the switch or the switch sticks in. With the new plug/socket installed the wiper motor action definitely improved.
The next step was to measure the voltage directly on the motor. On slow speed it measured 7 volts but high speed measured 12 volts. This suggests that much more current was being drawn on the slow speed. By connecting battery 12volts on slow speed there was an immediate improvement, suggesting the wiring was inadequate. Connecting battery 12 volts on high speed made only a marginal difference. It is worth noting that all wiper selections except high speed operate at the low speed so that any improvements to the low speed operation will also affect intermittent, single wipe and wash/wipe functions. The basic wiper circuit on my 1996 Griffith is seen below, contrary to common wiring code practice TVR used blue/green wire for the low speed motor connection and red/green for the high speed connection. The usual convention is to use red/green for slow speed and blue/green for high.
A simple 30 Amp make/brake relay will enable +12 volts battery volts to be connected to the motor when the wiper switch is operated for slow speed When improvements were made to the window motors I installed a standard domestic earth terminal block to the bulkhead (obtained from Screwfix) and used a spare terminal on this for the +12 volts feed to the new wiper relay. See photo below left. The plastic cover was an old 35mm colour slide container lid cut to suit and originaly fixed with silicon sealant but the sealant caused rapid corrosion so was removed.
The blue/green wire from the wiper switch can conveniently be found entering the dash just above the steering column see photo top right. The wiring needs to be cut here and a new wire soldered to the wiper switch end to switch the relay. As two relays had already been mounted on the bulkhead for the window motors it was a convenient place to mount the new wiper relay, see pic below right. It is worth checking before fixing the relays that the dash will not be obstructed when replaced. I initially had them to the right and this fouled the speedometer.
The wiping action is now much improved and inspires a lot more confidence.
The wipers have always managed to clear the screen on both slow and high speed but they seemed only just to manage the task and would struggle unless the screen was very wet.
First I decided to remove the multiway socket from the motor socket but found that it was stuck fast. Eventually I freed it but in the process pulled one of the pins out of the plug and self parking switch. I found that the pins and socket were covered in rust, due no doubt to rain water and hardly the best conductor of electricity. So the first job was to replace both the self parking/switch and the mating socket. There are many suspect replacement items on the market but I found the ones supplied by Car Builder Solutions were identical to the original Lucas items. As an amusing aside and to illustrate the possible problems with using pattern replacement wiper motor parts have a look at: Wiper Problems
Fitting the self parking switch onto the motor frame is a bit fiddly and it is worth checking before reinstalling the wiper motor that the self parking switch actually works as if the switch is not located accurately the cam on the gear wheel either misses the switch or the switch sticks in. With the new plug/socket installed the wiper motor action definitely improved.
The next step was to measure the voltage directly on the motor. On slow speed it measured 7 volts but high speed measured 12 volts. This suggests that much more current was being drawn on the slow speed. By connecting battery 12volts on slow speed there was an immediate improvement, suggesting the wiring was inadequate. Connecting battery 12 volts on high speed made only a marginal difference. It is worth noting that all wiper selections except high speed operate at the low speed so that any improvements to the low speed operation will also affect intermittent, single wipe and wash/wipe functions. The basic wiper circuit on my 1996 Griffith is seen below, contrary to common wiring code practice TVR used blue/green wire for the low speed motor connection and red/green for the high speed connection. The usual convention is to use red/green for slow speed and blue/green for high.
A simple 30 Amp make/brake relay will enable +12 volts battery volts to be connected to the motor when the wiper switch is operated for slow speed When improvements were made to the window motors I installed a standard domestic earth terminal block to the bulkhead (obtained from Screwfix) and used a spare terminal on this for the +12 volts feed to the new wiper relay. See photo below left. The plastic cover was an old 35mm colour slide container lid cut to suit and originaly fixed with silicon sealant but the sealant caused rapid corrosion so was removed.
The blue/green wire from the wiper switch can conveniently be found entering the dash just above the steering column see photo top right. The wiring needs to be cut here and a new wire soldered to the wiper switch end to switch the relay. As two relays had already been mounted on the bulkhead for the window motors it was a convenient place to mount the new wiper relay, see pic below right. It is worth checking before fixing the relays that the dash will not be obstructed when replaced. I initially had them to the right and this fouled the speedometer.
The wiping action is now much improved and inspires a lot more confidence.
The basic Wiper Circuit
12 Volt Terminal Block
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Window Motor and Wiper Relays
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