The MGA With An Attitude
BRAKE LIGHT SWITCHES, Good Ones or Bad Ones - ET-119A
There has been lots of discussion about cheap brake light pressure switches that fail early in life, so there must be a lot of them on the market. There is also some discussion about how to install a relay to reduce the electrical load on the pressure switch in an attempt to make a garbage switch last longer. I would never recommend the relay installation as it unnecessarily adds complexity and an increased probability of some of the added parts failing. more work to install, and more future maintenance problems. For those inclined to be curious, click the off-site link to the Brake Light Relay. Another approach is to install a mechanical switch on the brake pedal. I don't recommend that either for the same reasons, non-standard parts, and bother to install.
The correct answer is to buy a good pressure switch that will not fail. The trick is how to figure out which ones are good or bad before you buy one. It is likely that they all work when new, and there is no visual clue for reliability when new. If you were so inclined you might run a test for required switching pressure and contact resistance. The thing should switch on with about 20 psi pressure, and electrical resistance should ALWAYS be less than 1/4-ohm (250-milli-ohm max). A switch might meet these requirements when new and fail prematurely anyway, so these test may not be much benefit in evaluating a new switch (unless it is actually bad when new). The bad switches fail due to very cheap electrical contacts inside that may burn and increase resistance with normal use. As far as I can tell, no pressure switch has ever failed due to use of silicone brake fluid, so you may ignore any mention of that issue.
The objective here is to identify bad switches by reporting field failures. It is not easy to get people to report a failed part when a replacement costs less than $10. The proper action for a switch that fails early is to report it to the supplier immediately. If you can take enough time to bitch about it on a web forum, then you should also name the supplier, the suppliers part number, and anything else you can tell to identify the part. If you will do that, then I will be happy to list it as a faulty part, which will in turn give the supplier a chance to get the problem fixed (and for buyers to avoid it until it is fixed). So far I hear lots of complaining but precious few reports with useful information.
The brake light pressure switch is otherwise a generic device, widely available. The threaded end needs to be 1/8-NPT (tapered pipe thread, 27 threads per inch). Original terminal style (for MGA) is set screw post, but you can use a switch with push-on terminals by installing Lucar connectors on the harness wires. I will list here as many cross reference numbers as I can find, or as many as people will report. All switches will be assumed to be good until someone reports failure of a switch with a specific manufacturer and part number. If you have a failed switch it would be good if you can cut it open and get a close up picture of the failed contacts. It would also be good if you can persure test a switch, either new or failed, to determine the required pressure for switching. See follow-up reports good or bad on the following page.
3H1894 - Switch - stop lamp (original BMC part number)
3H1894 - kipmotor.com (Metrololitan parts)
3H1894 - MGOC_Spares
141-700 - LBCarCo
141-700 - Moss Motors -- ET-119G3 ---------->>
 Once reported good, but now Kwown Bad
1S10683 - Rock Auto (Airtex/Wells) - {SW8048}
201-0130 - Beck/Arnley - spade terminals - (17M8)
20010 - FAE - known bad
21020 - FAE - known bad - Found in a box with Duralast no. RB401, which was previously good, so now the Duralast RB401 is also Known Bad.
31082 - Lucas (34445; 34542; 34765)
34542 - St George Ltd - (141-700; 201-0130; 31802; 34765; 542-110; C16062; SMB423; SPB400)
458 - Lucas (vintage switch, had a very long life)
51600 - Intermotor -- Once reported to be good, but more recently shown to be Known Bad -- ET-119G3
51620 - Intermotor
542-110 - LBCarCo - spade terminal
542-110 - Moss Motors - spade terminal
6DF 007 669-001 - Hella - spade terminal - (might be unique to Europe)
72023-51E - Harley Davidson - Known Bad------------------->>
8-341 - Victoria British Ltd
80174 - Painless Performance Wiring - Low pressure operation 55-120 psi (non-standard terminals, but special connector included)
C16062 - MGOC - spade terminals
HL2 - MNW Isetta 300 - (Lucas 31082)
IM5162 - EnglishParts.com - (141-700; 293699; 2A5304; 3H1894; 62057; BMK1278; C16062A; IM5162; SC332; SC333)
LVRB352 - Motaquip
PB707/ES1662 - Park-Remax (Made in England) - - New old stock.
Replaces 31802/34542. Reported as good by Bob Macherone who owns Sports Car Shop in Eugene, Oregon.
R4006-4 - ISSPRO - spade terminal - Known Bad - incorrect application (4-psi)
RB401 Duralast (Made in Spain) - Autozone - Looks Like A Winner - 1020 FAE
This one lasted 3-yr 8-1/2 mo, 130,204 mi in service. Number on bottom: 21020
RB401 Duralast (Made in Spain) - Autozone - May now be bad
RB401 Duralast (Made in Spain) - Autozone - Almost certainly bad now
S194 - BWD (Borg Warner) S194 - peg terminals, from O'Reileys - Known Bad
S550 - Advance Auto Parts - Known Bad
S550 - Borg Warner - Known Bad
SBA2118 - CarQuest SBA2118 - Known Bad
SL134 - NAPA/Echlin ECH SL134 - peg terminals
SL134SB - NAPA/MPE MPE SL134SB - (Mileage Plus Electrical) - peg terminals
SL147 - NAPA/Echlin ECH SL147 - spade terminals - Known Bad
16271 - NAPA 16271 - spade terminals - Known Bad
SLS273 - Rock Auto (Standard Motor Products, made in USA) - {31440, 34765, E852}
SLS27T - NAPA (Standard Motor Products, made in USA) - peg terminals - Known Bad
SMP-SLS273 - Summit Racing (Standard Motor Products, made in USA)
SPB400 - Lucas (31082)
SMB423 - Lucas - with lucar terminals
SW32 - Ron Francis Wiring - low pressure operation 20-50 psi (non-standard terminals, but special connector included) - similar to 80174 Painless - Known bad (reported failures)
SW8048 - AutoZone
XBLS200 - Commercial Ignition
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Also used on:
AC Cobra 64-65
Alfa Romeo 1750
Berlina GTV
Spider Veloce 68
GT Junior 1300 66-68
Sprint 65
Aston Martin DB2-4 57
Aston Martin DB4 58
Aston Martin DBD 58
Austin
1100, 1300 +GT 69-74
1300 GT 70-74
A60 Cambridge 1600 66-69
Mini 59-69
Mini 850, 1000 64-73
Mini Clubman 1000 70-73
Mini Cooper 62-65
Mini Cooper S
Vanden Plas 1300
Princess 67-74
Austin Healey
Sprite MKI 62-66
100, 3000 BN1-BJ8 53-67
BMW Isetta 300 54-60
Borgward Lloyd Alexander 57-60
Daimler Limousine 69-92
Sovereign 2.8, 4.2 69-71
Fiat 238 69-83
Ford Anglia 63-67
Escort 1100,1300 68-70
Escort Twin Cam 68-71
Hillman Hunter 66-70
Husky 56-66
Minx 50-67
Jaguar 240, 340 67
420, 420G 66-70
Mk2, MkVII, VIII, IX 63-66
Mk3.8S
E type 61-71
E type DH,FH Cp 4.2 69-72
XJ6/XJ 2.8, 4.2 68-71
XK120, XK140, XK150 55-56
Land Rover series IIA 62-69
LTI Carbodies
FL2 Hire Car 2.25D 72-77
FX4 Taxi 2.25D 72-85
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Maserati Bora 4700 70-78
Maserati Bora 4900 78-82
Maserati Khamsin 72-82
Maserati Merak SS 72-83
MG 1100 63-67
1300 68-71
MGA (all) 55-62
MGB 62-67
MGB GT Roadster 63-74
MGC GT Roadster 68-69
Midget 61-66
TC, TD, TF 45-55
Morgan Four Four 1600 82-85
Morgan Plus Eight 3.5 68-74
Morris 1100, 1300, GT 69-73
Mini 59-69
Minor 1000 63-67
Oxford 1600 67-71
Traveller 69-73
Nash Metropolitan (all)
Rover 2000 63-72
RTI KC Walk-thru trucks 70-78
PB 1500, 2000, 2500
Spacevan Diesel 69-76
Singer Gazelle 57-58
Sunbeam Alpine 63-67
Arrow 67-69
Rapier 60-67
Tiger 64-67
Triumph 2000 66-68
GT6 68-70
Herald 59-67
Mayflower 50-53
Renown 50-52
Spitfire 62-67
TR2, 2A 54-55
TR3 to TS60000 55-62
R4, 4A 62-67
TR250 68
TR6 69-70
Volvo 544 57-61
Volvo 122 62-68
Vauxhall Victor 59-62
Wolseley 1100 68
1300 68-71
1500 58-64
16/60 69-70
Hornet 63-69
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Addendum 1/28/18:
These are cross references for the spade terminal version of this switch. Beware, I have just cut another one open and found it to be bad, but the cross reference numbers are still valid for spade terminal switches. I was greaty disappointed that the bad FAE 21020 switch is now found in the Autozone Duralast RB402 package (which previously contained a good switch).
Audi 113 945 515 B
Bosh 0 344 004 010
FAE 21020
Hella 6DL 003 261-041
Hella 6DL 003 262-001
M.B. Trucks 000 545 65 09
Skoda 193 595 294 (Oktavia 1.2 Super)
TRW 171023
Volkswagen 113 945 515 B
APPLICATIONS:
Alfa Romeo 1750-2000 1968-72
Alfa Romeo 2600 Berlina 2.6 1962-69
Alfa Romeo 2600 Spider 2.6 1961-65
Alfa Romeo 2600 Sprint 2.6 1962-66
Alfa Romeo Giulia 1600Super 1964-69
Audi 50 0.8 1976-78
Austin 1000 MK II 1100 1970-74
Austin 1000 MK II 1300 1970-74
Austin 1000 MK II 1300GT 1970-74
Austin Apache 1300 1971-74
Austin Apache 1300 TC 1971-74
AH Sprite MK III Cabrio 1.1 1964-66
AH Sprite MK IV Cabrio 1.3 1966-71
Daf Old/Various
Daimler 2.8-5.3 Sovern 2.8 1969-75
Daimler 2.8-5.3 Sovern 4.2 1969-73
Daimler Limousine 4.2 1968-91
Ebro Old/Various
Fiat 500 0.5 1957-61
Fiat 500 0.5 1965-75
Fiat 500 0.6 1973-76
Fiat 500 Kombi 0.5 1960-66
Fiat 600 0.6 1955-61
Fiat 600 0.8 1960-71
Fiat 850 0.8 1964-72
Fiat 850 0.8 Special 1968-72
Ford Escort I 1100 1968-76
Ford Escort I 1300 1968-76
Ford Escort I 1300 GT 1968-71
Ford Escort I 950 1968-74
Ford Escort I Kombi1100 1968-76
Ford Escort I Kombi1300 1971-76
IVECO Old / Various
Jaguar E-Type 2+2 4.2 1966-75
Jaguar E-Type 3.8 1961-64
Jaguar E-Type 4.2 1964-75
Jaguar E-Type Convert. 3.8 1961-64
Jaguar E-Type Convert. 4.2 1964-75
Jaguar XJ 6 2.8 1968-73
Jaguar XJ 6 4.2 1969-75
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John Deere Tractors
Land Rover 88/109 2.3 4x4 1963-86
Land Rover 88/109 2.3 D 4x4 1963-86
Land Rover 88/109HT 2.3 4x4 1963-86
Land Rover Santana Old/Various
Leyland/DAF Old/Various
Mercedes Benz Trucks Old/Various
MG 1300 Mk.II 1300 1967-70
MG Magnette 1.6 1961-68
MG MGB Cabriolet 1.8 1966-80
MG MGB GT 1.8 1966-80
MG MGB GT 3.5 1973-76
MG MGC 3.0 1967-69
MG MGC GT 3.0 1967-69
MG Midget 1.1 1964-66
MG Midget 1.3 1967-74
Mini 850 1967-79
Mini 1000 1967-84
Mini Old / Various
Morgan Four Four 1.6 1968-82
Morgan Plus Eight 3.5 1968-86
Riley Elf Mk.III 1.0 1963-68
Riley Kestrel 1100 1965-67
Riley Kestrel 1300 1967-69
Rover A60 Cambridge 1.7 1962-69
Seat 600 D 0.8 1963-70
Triumph Spitfire 1.2 MK I 1962-65
Triumph Spitfire 1.2 MK II 1965-67
Triumph Tr 4 2.0 1961-65
Triumph TR 4A 2.2 1965-67
Volvo P 121 1.8 1959-66
Volvo P 121 1.8 1967-71
Volvo P 121 2.0 1968-71
Volvo P 122 S Amazon 1.8 1959-71
Volvo P 122 S Amazon 2.0 1968-71
Volvo P 122 S Am.Kombi 1.8 1961-67
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