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Oystein · Guest

I have an 1991 33 1.7IE (8V) sportwagon 4x4 with cat, and it consumes approx. 0.9 litres of fuel per 10km on long trips. Too much, I think.
I tried the "Test no. 5 - check on engine water temperature sensor (CU pin 8) in the "electrical troubleshooting procedure" in the workshop manual, but I'm stuck.
The test has the following steps:

"1. Check between pin 6 of CU connector and ground. A resistance value depending on engine water temperature as per curve."
Q1) Do they mean pin 6 or pin 8 (the title says pin 8)?
-Anyway, I have no connection between either of them and ground.

"2. Then, check wiring continuity between electronic CU connecter pin 6 and brown wire on S7 temperature sensor"
- NO, no connection there.

I do have connection between the brown wire on the temperature sensor and pin 7 on the ICU (a small black box behind the battery). But I don't know if the connection is broken inside the ICU or between the ICU and the ECU.

Q2) Does anybody know from which pin on the ICU the temperature signal goes from the ICU to the ECU?
I have no connection between ECU pin 6 or ECU pin 8 and any of the pins on the ICU.

Q3) Does anybody know what the ICU does with the temperature signal? Can I just by-pass the ICU and make a direct connection between the ECU and the temperature sensor?

bobbber · Posted: Tue Jul 05, 2005 10:10 pm Post subject:

Uh, when you say connection - I think you should be testing for 'resistance'?????
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Fiat Bravo 165 Sport

Guest · Posted: Tue Jul 05, 2005 11:45 pm Post subject:

bobbber · Posted: Wed Jul 06, 2005 8:44 pm Post subject:

Yes - this is a difficult point seeing as the manual does indeed say pin 8 on the title and then pin 6 in the text body.

Shocked

However, it's pin 8.

The reading at cold should be between about 2k OHMS and 6k OHMS. So if you have a tester with various resistance on it you should be setting it to at least 10k OHM. A lower setting would make it appear as though there was no continuity at all.

A warm engine (80 degrees C) the resistance should be around 300 (ish ) OHMS.

You should check you are connecting across the correct pin to ground too... pin 8 is the furthest one from the cable on the 'fat' side of the connector (i.e. the side with 8 pins).

Let me know if this helps - this diagram (though unfinished) may help too :
http://www.alfa-restoration.co.uk/jetronic/connectorpins.html

Good Luck,

Bob
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Fiat Bravo 165 Sport

Guest · Posted: Thu Jul 07, 2005 6:43 pm Post subject:

Thank you, Bob, for a very helpful description!
And the Alfa-Restoration.co.uk-pages are very good.
What I ment when I said "connection", was "continuity".

I know the temp.sensor is broken (I broke it myself when I removed it), so that is why I am testing for continuity in the wiring, and not resistance.
I have bought a new sensor, so as soon I have continuity between pin 8 on the ECU and the end of the brown wire (which is unplugged from the sensor at the moment), I will test for resistance in relation to temperature.

The problem now is that I think the wiring is broken somewhere between pin 8 on the ECU and the ICU, because I do have continuity between the brown wire-end (where the temp-sensor is) and pin 7 on the ICU.
So that leads to my Question 2 and 3 in the first posting!

bobbber · Posted: Thu Jul 07, 2005 10:43 pm Post subject:

So currently you just have the plug for the temperature sensor (with the brown and black wires)... correct? It's not plugged into the sensor at the moment. Therefore :

1. You will should have no connection between pin 8 and ground (G60)
2. Should have continuity between pin 8 and the brown wire.
3. Should have continuity between ground (G60) and black wire (sensor end).

Why you have connection between brown wire and pin 7 - I have no idea. As far as I know - you can remove the brown and black wires from the sensor plug and replace with new wires to pin 8 and *any* ground.

Does that help?

Bob
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Fiat Bravo 165 Sport

Guest · Posted: Fri Jul 08, 2005 2:53 pm Post subject:

Hi

I`m not an expert on this subjet.
But my previous S2 1.5 TI, developed a "gremlin", that can be of some help to you.
When i switched the turn signal to the right, the wiper started working...
The right front light was dim and sometimes, when i turned it on, the wiper
would make a sweep of the windshield.
What i discovered:
-near the battery there was a connector (front service connector), that i discovered that was full of "mud". Whenever i switched turn lights, front lights, wiper, the wires involved were all close "neighbors" on that service connector. So thanks to "mud" the voltage was being distributed by all wires that were dirty...

Bellamachinna · Posted: Fri Jul 08, 2005 3:02 pm Post subject:

That was me above...
Forgot to Log in
P.Camilo
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All'interno della mia macchina, vi sedete, tenete sopra e CHIUDETE IN SU...

Oystein · Guest

I'm sorry bothering you again, but it is difficult to explain the real problem.
1. I have NOT continuity between brown wire-end (that usually is plugged into the temp. sensor) an pin 7 on the ECU.
1. I have NOT continuity between brown wire-end (that usually is plugged into the temp. sensor) an pin 8 on the ECU.
3. But I do have continuity between brown wire-end (that usually is plugged into the temp. sensor) an pin 7 on the ICU (Injection control unit, a small black box behind the battery). In my car the ECU and the ICU are two different boxes.

So that is why I ask:

-Does anybody know what the ICU does with the temperature signal?
-Can I just by-pass the ICU and make a direct connection between pin 8 on the ECU and the temperature sensor?

-Does anybody know from which pin on the ICU the temperature signal goes from the ICU to pin 8 on the ECU?

Guest · Posted: Tue Jul 19, 2005 9:10 pm Post subject:

Problem solved!
I have now checked the wiring all the way, and found a solution to the problem: I have mixed up two sensors.
The engine has (a least) two temperature sensors to control the running of the engine:

1) One is is located on top of cylinder no. 3 and is connected to ECU pin 8.
2) One is is located on top of cylinder no. 1 and is connected to pin 7 on the Iginition Control Unit (sometimes called "power module"). This is the mysterious black box behind the battery and advances the ignition when the engine is cold. You can read about this sensor in "Check of spark advance variation" under "Injection system troubleshooting" in the Jetronic manual.

Thank you for your patience!

bobbber · Posted: Wed Jul 20, 2005 10:33 am Post subject:

Back on the road now?
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Fiat Bravo 165 Sport