Morning -

86 SIII FI - no EGR

Collecting some docs/info so I know my way around the motor bay better and waned some clarification of the four temp sensors/switches on the water rail intake side. Below is pix of:

- Thermal switch (EAC3762)
- Coolant sensor (EAC3927)
- Temp transmitter (unmarked on this diagram)
- Thermo time switch (EAC1385)

I have rough ideas that one is your basic sensor for temp gauge, one interacts with cold start valve, one interacts with ECU and not sure of the fourth. Can some kind expert just give a the quick lowdown on each.
I also did a simple search and the same term brought up a picture of three of the four So Google needs help too - ha ha !
Very much appreciated

Randy in Raleigh

 

The fourth switch interacts with the "air switching module"...which is about the size of a pack of cigarettes, silver, mounted on the RH inner fender.

The switch and module control the diverter valve at the back of the air injection pump and the purge valve for the fuel vapor cannister. From the diagrams it appears that the switching module also has a bearing on switching from open loop to closed loop operation....but I've never seen anything from Jaguar going into any details on that.

From memory the switch is normally closed and opens at about 155ºF

Cheers
DD

 

The Thermo Time switch provides the ground for the Cold Start Injector. Positive voltage for the Cold Start Injector comes from the starter circuit. The TT switch will provide a ground for 0-8 seconds depending on coolant temp. It has an internal heater which prevents it from operating for too long and the temp probe prevents it from operating when not needed. And, since the CSI is powered by the starter circuit, it will only operate with the key turned to 'start'.

The sensor for the dash temp gauge provides a variable resistance to ground.....as on virtually any other car out there.

The temp sensor for the fuel injection ECU does the same thing: variable resistance to ground as is commonplace with fuel injection

Cheers
DD