temperature Sender info required

[Tonyd]

Hi guys,

Now that the Lexus V8 is running happily in the Cobra I'm just connecting up the last few wires before we start trimming the interior.

I've spent many a good hour poring over the wiring diagrams, done a search on this site, crawled all over the engine but I still cant see how I get a signal for the water temperature gauge from a toyota temperature sender on the engine.

I can see the EFI fuel sensor but I can't see the sensor for the temperature gauge itself, does the Lexus have one and where on the engine is it? The cooling fan is switched by a sensor in the radiator so I know the car isnt overheating but it would be nice to get a fully functioning instrument set.

Perhaps I have the wrong end of the stick and the EFI temp ensor is used for both purposes. If so how can I emulate how Lexus use this sensor given the fact that I only have the ECU and its associated engine loom wiring. The breakers yard have now crushed the donor car, so if I need an instrument ECU it looks like I will be going for an aftermarket sender.

Also is it possible to piggy back a signal off the rear speed sensor to run an electronic speedo without the piggyback upsetting the ECU, if so how do I go about it.

Once I finished tidying up the wiring the Lexus Cobra only needs its wheel and tyres, its interior and instruments, a windscreen and a Single Vehicle Approval Certificate from the govt and its time to hoon about and see what the standard Lexus grunt is like in something that only weighs 1000kg.....Unfortunately I have to sell the Beemer Cobra first to get the cash to finish the Lexus Cobra.........

Any advice on the two queries above gratefully received.

Cheers,

Tony

 

[Muzza_NZ]

Hi Tony,
from memory the temp sender is on the water bridge beside the ecu temp sensor and cold start injector sensor. Its the only single wire one there (the left most one from the front I think) It appears to have the same temperature response as other toyota senders (ie logarithmic)

Hope that helps,

Muzz

 

[Cobber]

Tony,


Good to hear things are getting close. The sender is under the front cover.
I can't hlp with the speed sensor but I think you are on the right track.

 

[Tonyd]

Thanks guys, I thought that sensor was the efi sensor but you're right, its the only one with a single wire.........

many thanks,

Cheers,

Tony

 

[GSMnow]

Assuming you have an A341E (or a340E for that matter) I might be able to help. I have been running around trying to figure out the speed sensors myself, and what I have come up with is a couple possibilities. Depending on the year of the trans it will have 1 or 2 speed sensors in the tail housing. The one they all seem to have is a reluctor magnetic sensor (only 2 wires) that puts out an AC waveform at a rate of 4 pulses per rotation of the driveshaft. The voltage of the wave will increase with speed. This is fed to the ECT labeled SP2. This may be fine for a programmable speedo like an AutoMeter electronic unit. Additional load on this sensor may reduce its signal a little, and may make it fail to read at very loaw speeds. The stronger signal with speed though should make for no problems. The other sensor that does not seem to be in every one is a gear driven sensor that turns at a 3 to 1 ratio slower and puts out 4 pulses per its rotation, so after 3 rotations of the drive shaft it will put out 4 pulses. This sensor is usually a hall type with 3 wires, so it puts out a solid square wave pulse (probably just 5 volts). In the stock setup, this connected to the speedo first and then sent to the cruise control and ECU. This type of sensor can certainly drive an additional load without effecting the ECU. This sensor may be a reluctor type in some years, my diagrams only show two wires on some cars. If so, the same loading rules apply.

Gary M.