1976 water temperature switch

[saridout]

while i wait for my dad to inspect the switch on my car for markings, i thought i'd post these ignition diagrams from 1974 and 1976 model. i'm no good with electrical stuff, but it appears to me that the water temp switch in both years functioned the same way. thoughts?

i am a little confused though, cause i thought that my car was a california car, having an advanced emissions system, but the fsm says that only non-cali models had the water temperature switch. here is the copy from the fms:

"On the non-california model, the advance control relay and water temperature switch are provided. The temperature switch is a bimetal type. When the engine coolant is at low temperatures, the contact points are close and current flows through the relay, so that the transistor ignigion unit transmits advanced ignition signals. When the coolant reaches and fixed temperature and the bimetal temperature switch contacts are so opened as to not let an electrical current flow the relay, relay contacts are closed and another voltage is applied to the ignition unit, which transmits retarded ignition signals. In this way, advanced signal is changed over by the temperature of engine coolant."

[sblake01]

Looks to me that all the switch does is complete a ground until the temp reaches a certain level then it opens. If the temperature they open is the same then all you'd have to do is splice your 76 connectors onto the 74 wires. It wouldn't even matter if the wires got switched since all it does is complete a ground. These are the ones I have that open at 35 deg. C. I'm just not sure they would fit the water outlet.

Edited September 16, 2009 by sblake01

[saridout]

maybe it's the angle, but the threaded portion of that switch looks bigger than the switch on my car. do you have calipers? the threaded portion on my switch is 13.45 mm wide. also, dad got back to me with the markings on it. one facet says 509 and another facet says TB-14.

[sblake01]

Just measured it and it's just a shade under 17 mm. so, like I thought, they're too big.

[webdawg1]

Don't know if it's any help or not...the switch I have has the following info on it...

TB-14P

60-OFF

another facet has some sort or marking on it and 05 right below the mark...

next facet over has either 1.1 or 11 on it...(probably 11)

webdawg1

[saridout]

is that from your new N4202 switch?

[webdawg1]

yep...I can check on the old one two...75 280Z...

webdawg1

[webdawg1]

ok...on the old switch (which I might add was in pretty bad shape) it has...pretty much the same mark on one facet as the new one...503 on one facet...and TB-14 on the other facet...no other marks or info noted on the other facets...

webdawg1

[saridout]

the new switch for a 1974 260 has arrived, and it fits! i tested it on the stove, and it completes the circuit at about 90 degrees. the original switch, according to the FSM (pg. ET-16), closes the circuit at 134 degrees, and that's a difference i can live with.

i'll let yall know if there are any developments once i actually get the car running.

[Pomorza]

Just wondering if you got it to work. How exactly is it wired? Mine is in just as bad shape as yours. Please advise.

Jan

[saridout]

i'm still getting the engine put back into the car, so i haven't turned it on yet to see if it works, and even when i do, it's likely that there will be no way to tell if it's working. the new switch functions in practically the same way, the only difference being that it connects at a lower temperature (90F versus 135F).

if you choose to go with the 1974 switch like i have, you'll need to cut off the connector and put a ring connector on one wire that is large enough to go around the nearest bolt that attaches the thermostat housing. the other wire needs to have some more wire spliced onto it along with a bullet connector. that'll connect to a red wire coming off the same 4-prong plug as the thermal transmitter. look here for diagrams http://www.classiczcars.com/forums/showthread.php?t=30273&highlight=water+temperature+switch

note that it shouldn't matter which wire you use for ground on the new switch; they'll both work.

[PeterK]

While changing the temperature sending unit and cleaning the coolant temperature sensor the other night the two wires literally fell off my water temperature switch.

Correct me if I'm wrong, but if the switch is closed at cold temps (less than 134 F), then simply leaving the switch broken (open) will only affect the distributor timing/exhaust gas return when the engine is warming up. Am I correct in that once the coolant is above 134 degrees this switch would open and behave just like a broken switch.

And if I have it backwards, and the switch is open at temps less than 134 F, and closed at temps greater than 134 F, would I be able to simply ground the wire that previously connected the EGR solenoid to the temperature switch? (At least for the time being, until it is properly repaired).

Link to thread with wiring diagrams:http://www.classiczcars.com/forums/showthread.php?t=30273&highlight=water+temperature+switch