# Ram Air IV intake sensors



## Ram Air IV Judge (Sep 6, 2014)

This post goes out to all you Ram Air IV experts out there...
There are two tapped holes in the aluminum intake for water sensors on a Ram Air IV GTO. One I know is for the water temp gauge which is the one behind the alternator. It's the other one on the passenger side of the engine I want to inquire about. In pictures sometimes I see a electrical sensor with three wires going into it. I would think this could be a hot/cold light switch, however I do not see a hot/cold light on the GTO dash. Can someone please explain this? Also sometimes in place of the electrical switch explained above, there is a thermal vacuum switch which I believe is only on the RA IV automatic trans version. Am I correct here? I cannot seem to find any vacuum line routing for this TVS. Can anybody shed some light on the subject?


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## BearGFR (Aug 25, 2008)

The car will have a temperature gauge OR a temp "idiot light", not both. Both the temp gauge sending unit or the temp light switch screw into the same spot on the intake water crossover - the one nearest the thermostat housing. The other hole is for the vacuum control, which I'm pretty sure was used on all cars regardless of transmission. It's primary purpose was to serve as an emissions device. It altered the behavior of the ignition vacuum advance mechanism based on engine temp.

Bear


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## Ram Air IV Judge (Sep 6, 2014)

*Water sensors Ram Air IV*

What you say makes sense, however this picture shows both holes with electrical sensors. The one on the driver's side is the sensor for the gauge. Now note the three wire sensor on the passenger's side. What does that do? That's no TVS. Owner claims car is PHS original. He has pictures of the gauge clusters and I see no hot/cold light. Those wires have to go somewhere. So it's back to square one on what is the proper set up for the Ram Air intake for manual transmission or automatic transmission? Does anybody know?


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## Ram Air IV Judge (Sep 6, 2014)

*Water sensors Ram Air IV*

I've been doing some research on this subject. Please tell me if I am wrong. Apparently the 1969 Ram Air IV has the TVS sensor. Where the 1970 Ram Air IV has the electric sensor connected to a vacuum solenoid mounted behind the carburetor to one of its studs. This would perform the same function as the 1969 only it's electric. Vacuum lines for the 1969 are still not resolved. I would think one of the 3 lines going to the TVS has to be manifold vacuum. A second would have to be going to the distributor and the third is not clear where it would go. Perhaps it may go to the transmission if the car has AT. Now with the 1970 RA4 there are 3 wires going to the sensor. One has to be +12, the second has to be going to the vacuum solenoid and the third may be an internal ground and routed to the solenoid. I would need a sensor to test to prove this. Perhaps you guys who have one on the car could check. Just unplug the sensor and with your meter on ohms measure the resistance to ground on each terminal. If one terminal reads 0 ohms then it is internally grounded.


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## Boomstick (Sep 13, 2021)

Did anyone sort out what this sensor is for? I met a guy over the weekend that says its a california only thing and is looking for one which incidentally, my car came with one in the old intake so i'm giving it to him.


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## O52 (Jan 27, 2019)

The 69 engines used a single temperature switch for gauge or light indication only. This was mounted behind the alternator. A temperature operated vacuum switch (TVS) (automatics only) on the opposite side controlled the vacuum advance. Three vacuum lines connected to the TVS; Manifold, Ported, and Distributor Advance. Normally the distributor operated on ported vacuum. During an overheat condition the TVS would switch to manifold vacuum increasing the engine speed at idle. Once the engine temperature dropped it would go back to ported vacuum.


The only 'California' thing for 1970 was the fuel evaporative system.

As shown in the '70 service manual, the '70 engines used a single three wire temperature sensor mounted in the spot used by the previous vacuum TVS switch. This provided a ground path for the temperature indicator light indication and as a temperature controlled switch for the TCS solenoid. 
Ground for the TCS solenoid was a transmission switch that opened to ground in high gear, automatic or manual.
Vacuum was supplied to the distributor advance when the solenoid was de-energized. This occurred when engine temperature was below 88* or above 220*, or when in high gear. 

But the question remains of the second temperature sensor mounted behind the alternator. Although not mentioned in the service manual, the assembly manual shows a second temperature sensor for the Rally Gauge option. If the vehicle had a temperature light it would use the single combination TCS switch on the right side. Rally Gauge package would have a single wire sensor behind the alternator that would bypass the TCS indicator light terminal. For all V-8 engines, not just RA.


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