Clarification: Fan, Fan "Thermo" Switch, Fan Relay, ECU, T-Stat & Sensors?

[junglejustice]

Is there any connectivity between the cooling fan / fan-relay and the T-stat / ECU / dash in the standard Milano setup? (So, what about to the ECU and the temp-gauge/overheat warning light - where do they come in to play?

IOW - does the temp sensor on the T-Stat send a signal to the ECU, with the ECU in turn triggering the fan-relay, or is the T-stat and it's various sensors completely seperate form the ECU and the injection functions of the Bosch system? With the ECU, does the temp gauge still work then? How?

In that scenario, does the fan's on/off function come purely from a seperate switch on the radiator, which triggers the relay and turns the fan on - all completely seperate from the T-stat, those sensors and the ECU (other than sharing rounds and power from the main harness...?

Stated differently, with the stock ECU and engine harness removed, does the temp gauge and over-heat warning light still work? Where do they get their signals from? Also, with the stock ECU and engine-harness removed, how does the cooling-fan operate? (Is it on a seperate system between a switch on the radiator, the fan-relay and then the fan alone)?

On the race car (with all of the harnesses, sensors, relays and ECU removed, I have the GoTech Pro-X stand-alone driving the fan via one of it's auxiliary outputs, but on this street Verde, I want to maybe keep some of the stock relays, fan, radiator, sensors etc.

So, back-ground on the car that I am asking about:
1) 12 valve removed, 24 valve installed.
2) Stock 12 valve Milano t-stat housing and sensors utilized.
3) Stock chassis harness still there (but the stock engine-harness removed).
4) Stock ECU removed - now running GoTech ECU and harness.
5) Stock radiator, stock fan, stock relays still there, as well as any stock sensor(s) on the fan and radiator - should still be there.

[nizam]

JJ - on a stock Milano (L-Jetronic) the Bosch harness is completely independent of the car's (chassis) harness.

The fan switch located on the bottom of the radiator is independent of the ECU operations. When that switch closes, it triggers the fan relay to close the circuit and the fan turns on.

The temperature sender for the gauge is also completely separate from the temperature sender for the ECU. They are both located on the thermostat housing, as you know. The temperature sender has two blade connectors; one for the gauge and one for the warning light. The Jetronic signal comes from the other sender, with the typical Bosch connector (I think it has a blue receptacle).

Since the chassis harness is independent of the injection harness, as long as you didn't disturb the chassis harness in the process of grafting your GoTech injection harness into the car, all warning lights, relays, and gauges will work as normal.

[slyalfa]

The ECU is the white one. which you should be able to use with the new ECU.
and switching the fan relay from the ECU is a big time improvement. the switch in the bottom of the radiator is a problem on a older car. That part seems to get pluged up first. and the car will overheat due to that probe not seeing the temp of the coolent. I never overheated after having the ECU control the fan.

[AR4me]

Dear Mr. JungleJuice

When you pulled the LJet harness, you likely pulled the two wires that run from the thermostat (in the "V") along with LJet wires to the multipin connector at the overflow bottle - 3x3 or 3x4 pin, don't recall - this is the main interface between the LJet harness and the chassis harness. If, IF, I recall correctly the two wires are brown and orange (maybe orange-black). Just make a new short tail that connects to two the spades at the thermostat (IDed by Nizam) and the multipin connector mentioned above.

If this is black magic, go see a voodoo doctor and he/she should be able to get it going for you Or, simply go read my write-up on gtv6.com about the ancient Gotech install I did on the old, old, old 12v 3.0.

Jes

[SamW]

JJ,

I am running the GoTech Standard on my Vedre and the fan still works as normal, so they are independent, as does the engine temp guage, so it is independetn also.

[junglejustice]

Quote:

Originally Posted by AR4me Dear Mr. JungleJuice If this is black magic, go see a voodoo doctor and he/she should be able to get it going for you Or, simply go read my write-up on gtv6.com about the ancient Gotech install I did on the old, old, old 12v 3.0. Jes

[AR4me]

Yes, one relay is for fan, the other is for AC if I recall correctly.

If temp warning light does not come on during initial key-on, then perhaps your bulb is out. It will not work if it does not light during initial key-on!

I can check the diagram later and let you know the color of the wires that connect to the radiator temp switch.

Jes

[junglejustice]

Thanks Dr. Milano! Captain GoTech - out!

[AR4me]

Ok, if you have the manual... look at page 40-35. Lower left corner. L6 is the radiator thermo switch, and P2 is the fan motor. The thermo switch has a black (code N1) wire and a brown (code M1) wire. The brown wire goes to the relay, and the black wire joins the black wire from the radiator fan and goes to ground (at the grounds above the headlight if I recall correctly).

According to the manual the fan should be activated at 183-190F by the radiator thermo switch.

Edit: BTW, I think the radiator switch simply connects the two pins (brown and black wire) when temp gets to 183-190F, and opens circuit when temp is below. In that case, with engine at a temp where you would expect fan to be on, e.g. 195F (just look at temp gauge, close enough), pull plugs and put ohm-meter on two pins of radiator thermo switch and see if you get 0 Ohm. To fyrther verify you can also measure impedance with cold engine to see if you have open circuit. Actually, try connect black and brown wire with a clip to verify that fan comes on. Then you know operation, and you know you have the right wires.

Jes

[junglejustice]

Genius - just genius! Thanks!

Would I also have to attain a doctorate in order to be this electronics-friendly...? (Just want to know how long I still have to go)!

You're assuming that I have a manual! Manuals are for mechanics and for people who want to work on their own cars!

So, OK - yeah - jumping the two wires from the back of the thermo-switch, triggers the fan! It's getting the right signals - bad thermo-switch then!? Now, here's your favorite question Jes - "WHY"!? I mean - it worked just fine when the car last ran... Any fixes for it, before I replace it? I'll check resistance between the two connectors on it (but here again - the assumption is made that I actual own a multi-meter)! I'll get to it later today and report back!

I'm also going to check that little red LED on the dash and see if the bulb is out, or what!? Wonder how I can test it (and the sensor) first, before pulling the entire bloody instrument cluster AGAIN...!?

[AR4me]

The thermoswitch in the radiator is cheap - maybe $10. I have had one being intermittent, so they do fail. Just replace it.

You do have all the ARC connected, right? When you cycle the ignition key it is only the temp warning light that does not come on, right? Low fuel and oil pressure warning lights do come on, right?

Yeah, before pulling cluster, again, maybe make sure you have connection between the spade at the thermostat housing and the multipin connector at the coolant bottle at the firewall. Oh, wait, that requires a multimeter and maybe a manual

Jes

[junglejustice]

Quote:

Originally Posted by AR4me Oh, wait, that requires a multimeter and maybe a manual Jes

[AR4me]

If none of the 3 warning lights (oil pressure, temp, fuel) in the cluster work then I would look for ONE thing that affects them all, and not look at anything specific to anyone of them.

Try have the ARC circuit boxes (above the glove box) and the ARC light panel itself plugged in - I don't recall if this is like the brake lights (that won't work without the ARC circuit).

As for the oil pressure warning light: The sender on the 164S works just opposite the Milano sender - thanks Alfa So, make sure you use a pressure switch from a Milano and not 164 (assuming 24v is same as 12v). The sender for the oil pressure gauge should be the same for all, I think.

Jes

[junglejustice]

Nope - the V6 senders are different...

I wanted to do this in a seperate thread - it's nice to have these conversations a bit more segmented. obviously the three lights that are out are potentially related, but the sender-issue is a seperate one!

Also, for the record - I don't think that my fuel low-level light ever worked (ran out of gas once), but I am pretty sure that the temp-light and the oil-pressure light used to come on when I would cycle the key to the ACC ON position!

[AR4me]

Quote:

Originally Posted by junglejustice Nope - the V6 senders are different...