2G Radiator fans only work in ecmlink

[91dsm]

As the title states my fans only come on when I check the box in link. I waited until my coolant temp was at 210 and still nothing. They wont come on automatically. The last time I ran the car was a few months ago and I remembered them working automatically. Does anyone have any suggestions ?

 

[lasthope05]

If you can manually switch the fans on, check to make sure your coolant offset is set to 0 in the Misc tab.

 

[91dsm]

If you can manually switch the fans on, check to make sure your coolant offset is set to 0 in the Misc tab.

Thanks I just checked that its at 0.

 

[lasthope05]

I can't really think of anything else. If the ECU can override and turn on the fans it should also be able to control the fans. Perhaps update the firmware and the software if you haven't already.

 

[miguelmcv]

If they don’t turn on by them self, then check the cooling temperature sensor (thermal) it might’ve dead.

I will asume it’s a 1g, if it is a 1g, the sensor is mounted in the radiator, see if it’s working properly.
Also you can bypass the sensor by adding ground to the connector and see if the fans works.

 

[Jk's97DSM]

If they can be manually operated by the computer the circuit for power and ground is good. The signal that the relay needs to activate automatically is the issue.

 

[91dsm]

If they can be manually operated by the computer the circuit for power and ground is good. The signal that the relay needs to activate automatically is the issue.

So Im assuming its the ecu ? If so that's really a shame because everything else works.

 

[steve]

I don't have the full 1995 doc set handy but the 97-99 docs from the Manual CD show that the ECU and only the ECU have control over the radiator fan, and that the AC condenser fan low speed is controlled by the AC Computer, with the ECU controlling the high speed of the AC condenser fan.

According to the 2G DTM the ECU controls the fan speed based on the engine coolant temp and vehicle speed.

Since you can activate the fans using the DSMLink checkboxes it would seem that the output drivers on the ECU are good and leaves me wondering about the inputs from the ECT and VSS along with the configuration of Link for why it doesn't work.

A log would prove helpful.

 

[jed344]

This same issues killed a motor on a buddy's car at the track. Haven't looked into it yet but can turn fans on with ecm link but they will not come on by themselves. Just out of the blue after years of no issues. I normally run a 10 degrees offset in ecm link so it kicks fans sooner but that has no effect on this issue.

 

[miguelmcv]

When you activate the fans via ECMLINK, the ECU ignores the signal from the ETC and turns the fan ON, so saying that the ECU is not seeing the right signal from the ETC to be able to turn ON the fans.
Basically I’m saying the exact same thing as STEVE but in a different way.

 

[91dsm]

I will post a log over the weekend and see if that sheds light on anything. I appreciate all the responses.

 

[Jk's97DSM]

The ecu is fine if it turns them on in dsmlink. The inputs, i.e. sensors are most likely the issue. Check the wiring on most ECT sensors by jumping the connector. In that case it acts like a up to operating temp ect sensor turning the fans on. Can you see the ect sensor in link?

 

[91dsm]

Here is a log from today, I saw the coolant temp go up to 203 and still no fans. After installing my lc2 see the car is also running very lean at idle. Any ideas ?

 

[jed344]

You need to be logging closed loop, combined FT and maf RAW STFT. I cannot see your fuel trims. Why do you have the car locked in open loop?

 

[91dsm]

You need to be logging closed loop, combined FT and maf RAW STFT. I cannot see your fuel trims. Why do you have the car locked in open loop?

I had that set while doing some troubleshooting of my rough idle at startup ill take another log soon with that disabled. Thanks.

 

[91dsm]

You need to be logging closed loop, combined FT and maf RAW STFT. I cannot see your fuel trims. Why do you have the car locked in open loop?

Here is another log with that option disabled.

 

[91dsm]

Any feedback from the log ?

 

[Vegas Smith]

Here is a log from today, I saw the coolant temp go up to 203 and still no fans. After installing my lc2 see the car is also running very lean at idle. Any ideas ?

My understanding is that the fans dont turn on until around 210 degrees on a 2g so if you want them to come on sooner you can increase the coolant offset to trick the ecu into thinking the coolant temp is higher. I don't own a 2g so I can't verify that but that's what I've read.

 

[luv2rallye]

Here is when the 2g fans turn on with a stock ECU: https://www.dsmtuners.com/attachments/fan-operating-mode-2g-jpg.86862/

An aside note: On a stock 2g with stock 4 wire fans, the fan speeds are not obtained by voltage on a unique specific wire pair but rather voltage on wire combinations. Low speed is voltage on one positive wire (either lo positive or hi positive) and ground on one negative wire (either lo negative or hi negative) although most 2g dsm's use lo positive and lo negative. Medium speed is either voltage on two positive wires and ground on one negative wire OR voltage on one positive wire and ground on two negative wires (most 2g dsm's use the latter). High speed is voltage on both positive wires and ground on both negative wires.

 

[Tony818]

Was this issue ever resolved?