Ecu / Sad And Engine Temperature Sensor

[Phil205 1 1 Cars]

1.6 GTI - 1988 - Jetronic

 

The 2-pin connectors for the SAD and Engine temperature sensor are a pain to get apart.

 

I want to check the resistance measurement of the SAD and Engine temperature sensor. Presumably these are both wired to the ECU ? If so :-

 

1) Where is the ECU located ? Is it located behind the fuel filter ?

2) Presumably the SAD and Engine temperature sensor are wired to a connector at the ECU ? How easy is it to get at and take off this connector ? Does anyone know which pins are used for the SAD and Engine temperature sensor ?

 

Thanks,

 

Phil

[jim21070 2]

Yes they are Use a sharp, pointed object (like a scriber) to spring out the retaining clip and they'll then pull off easily.

 

The ECU is mounted up under the dash on the drivers side, up and beside the steering column. You'll need to take off the lower dash side (the bit with the cubbyhole) to get to the ECU

 

The Coolant Temperature Sensor is blue and has a blue two-pin connector. It is located on the side of the coolant block between the thermostat housing and the heater pipe. Access is easy once the AFM is removed.

 

The SAD is in the same position and has a black two-pin connector. Access is reasonable with the AFM out of the way.

[Phil205 1 1 Cars]

Yes they are Use a sharp, pointed object (like a scriber) to spring out the retaining clip and they'll then pull off easily.

 

The ECU is mounted up under the dash on the drivers side, up and beside the steering column. You'll need to take off the lower dash side (the bit with the cubbyhole) to get to the ECU

 

The Coolant Temperature Sensor is blue and has a blue two-pin connector. It is located on the side of the coolant block between the thermostat housing and the heater pipe. Access is easy once the AFM is removed.

 

The SAD is in the same position and has a black two-pin connector. Access is reasonable with the AFM out of the way.

 

 

Thanks Jim. I think that there was a bit of a misunderstanding.

 

Does anyone know which pins (of the connector to the ECU) are used for the SAD and Engine temperature sensor ?

 

Regards,

 

Phil

[jim21070 2]

Sorry Phil,

 

That is what happens when replying, drinking a cuppa and eating a Kit Kat

 

The Coolant Temperature Sensor connects to the ECU on Wire No. 10. The actual ECU pin number appears to be 13 according to this site:

 

http://www.ratwell.com/technical/L-Jetroni...r/Schematic.jpg

 

 

If you look at the ECU connector, you'll see the wire as if you look carefully it'll have "10" printed on it at repeating intervals. This applies to both ends of the wire. The other side of the sensor is earthed.

 

The SAD is not controlled by the ECU and should not be confused with the Cold Start Valve on the diagram in the link above. The SAD, in fact, takes its supply from the injectors.

 

Hope that is better!

[Phil205 1 1 Cars]

I took off part of the dash to get at the ECU. Not sure if I needed to, but I can now see the ECU in all it's glory !!

 

A few more questions. Please feel free to answer as much as possible :-

 

1) Does the ECU connector come off easily enough ? I was just a little wary about touching it in case I damaged the connector.

 

2) The connector for the Engine temperature sensor (blue with a blue two-pin connector) is hard to get at, so I thought check it at the ECU instead. Once I have the ECU connector removed, I should be able to check the resistance of the Engine temperature sensor . This is the resistance between ECU pin number 13 (wire 10) and ground ECU pin number 15 (or 17 or 35), is that correct ?

 

http://www.ratwell.com/technical/L-Jetroni...r/Schematic.jpg

 

3) What is the Cold Start Valve in the diagram above, if it is not the SAD ?

 

4) I would like to check the resistance of the SAD (45-55 ohms at 20 celsius ?). I can't get at the connector. Where is this wired to ? If this goes to the injectors, whereabouts ?

 

5) I am having idling problems (only on cold / wet days, not on summer days). The CO has been checked and was 2.3 => 2.8 %, it should be 1 => 1.5 %, so the garage recommended changing the AFM. I would prefer to test the AFM (and above) to prove that it is faulty first, hence my questions. Has anyone run through the tests in the haynes manual (see Fuel injection system - complete test - page 95). This should tell me what is wrong, shouldn't it ?

 

6) Is it easy to remove then replace the AFM ? Would the mixture need to be readjusted with an allen key and CO meter ?

 

Thanks in advance.