FWIW...While perusing throne room pubs...
"PS Monthly Issue 542 JAN 1998 pg 7
Ditch Brake Light Switch
There are still some 2.5 ton trucks out there with the old hydraulic
fluid operated brake light switches.
They are safety hazards.
The switch can blow an electrical connector pin, dumping all your
hydraulic fluid.Then you have no brakes.
Replace that switch with an air operated switch, NSN 5930-00-789-6192.
TM 9-2320-361-20 shows the new switch. To install the switch, you need a
conversion kit, NSN 2530-01-105-5025.
The kit brings the switch, instructions, mounting hardware, and a
1/2-in. elbow. Some trucks need a 3/8-in. elbow, NSN 4730-00-289-0155, so
measure the tubing to find out which elbow you need."
The article has an OLD and NEW drawings of the switch. The NEW drawing
has the switch on the air (BOOSTER) side of the brake system, not the
fluid ( MASTER CYLINDER ) side. Might be worth checking if you have an
M35XXX series that came out of DRMO before the date of this article.
This might not be clear in the above info, but gives you a heads up on a
potential problem.
"We now return you to your regularly scheduled PM. "
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