Laptop not talking to ECU (ECU had been damaged by jump starting)

[Russ Stein]

I recently acquired a LHD 1987 911 with a single condenser Electrocooler system fitted. My issue is that the compressor will not cycle on at all. We have verified a correct installation of the system, pin-out tested all wiring against the installation manual, and seen that we have 80 psi static pressure in the system as well. We also have bypassed the contactor (temporarily) so as to assure correct amperage to the compressor. Everything is working except the compressor. Now we need to talk to the ECU to find out what is going on, but at this point can't talk to it.  Serial drivers load automatically to our Lenovo PC fine when the supplied USB cable is plugged into the PC, but there is no response when the cable is plugged into the ECU. Apparently we must have the firmware (zip file) to load the puTTy utility program,,  but the website in the manual referred to as a source for the zip is now non-existent?. Can you help with a source for the needed firmware file?   

Thanks in Advance!

[Jonny Retrofit]

Sure, it's here (Electrocooler v1.17):  https://www.classicretrofit.com/pages/manuals-and-software   

You say the system is 'working' apart from the compressor.  Does the blue button illuminate?

[Russ Stein]

Yes, the circular blue LED around the button illuminates at the low level on the car's starting, and then brightly when button is depressed and the blower fan is on (via the OE slide control), and of course the condenser blower fan is running as well. One can run the vehicle for an extended period (idle or driving), but still no compressor operation, hence no "cold" air output, only ambient. Our current temps here run about 30-32 degrees C. The vehicle is currently fitted with a 120 amp alternator and idles at 1000 rpm, so I feel the ECU is never seeing a low amp condition; voltage is always showing 12.5 at the battery.

[Russ Stein]

By the way, the manuals-and-software link you referred to does not have and firmware zip files that I could find on anywhere at that location. But, then I've not always been the sharpest knife in the kitchen...

[Jonny Retrofit]

On 6/25/2024 at 7:31 PM, Russ Stein said:

By the way, the manuals-and-software link you referred to does not have and firmware zip files that I could find on anywhere at that location. But, then I've not always been the sharpest knife in the kitchen...

On the right of the page - Electrocooler v1.17(new):

[Jonny Retrofit]

On 6/25/2024 at 7:00 PM, Russ Stein said:

Yes, the circular blue LED around the button illuminates at the low level on the car's starting, and then brightly when button is depressed and the blower fan is on (via the OE slide control), and of course the condenser blower fan is running as well. One can run the vehicle for an extended period (idle or driving), but still no compressor operation, hence no "cold" air output, only ambient. Our current temps here run about 30-32 degrees C. The vehicle is currently fitted with a 120 amp alternator and idles at 1000 rpm, so I feel the ECU is never seeing a low amp condition; voltage is always showing 12.5 at the battery.

Hmm, If this is our standard 911 system and the condenser fan is on, the compressor has to be running.   The ECU only switches the condenser fan on if the compressor draws over 30A - e.g. it has to be running to do that.

[Clifton]

Hi. We have the same issue

 

We installed new ac electric and the compressor is not starting. 

 

I checked all wiring and voltages according to the pin out and everything seems fine. 

 

Then i tried to connect laptop to ecu with putty but black screen. I noted when moving the jack plug out and in some data trying to display. 

Any Help please?

[Jonny Retrofit]

I would check the wiring inside the jack plug.

[Clifton]

@Jonny Retrofit i checked it and its good. I noted that on the blue cable going to comptlressor there is no ground

[Jonny Retrofit]

@clifton

Have you followed these checks in this thread below?

 

 

The blue wire in the compressor control cable gets its ground from the ECU which has 3 ground wires on the loom terminating in a ring terminal.  Is that ring terminal connected.

 

 

[Clifton]

@Jonny Retrofit we have 6 small black wires connected and one large from the compressor. 
to be 100% we connected them directly to the battery negative. 

[Jonny Retrofit]

So did you check continuity from the blue wire to the chassis ground/battery negative?

[Clifton]

Yes. There is no continutiy. As well i checked

from red of compressor to blue 0v

from red of compressor to earth/ground 12v. 
so there is 12v but no ground

[Jonny Retrofit]

So maybe a bad pin or the blue wire is broken/disconnected?  You can gently open the ECU case and see the connection inside.

We do test every ECU that leaves here.

[Russ Stein]

Jonny,

After some delay, back on task. Still no compressor, but more information. Updated firmware from 12.6 to 1.15, verified compressor brand as Benling, verified compressor as running on 12V (third line list text reads INV Normal [0]. Then checked ECU to compressor harness; all female connectors passed the resistor wire test (tight!). All four leads tested correctly per your “More advice on diagnosing a non-starting compressor” post. I thought I had it nailed when my ECU output for the yellow “enable” lead was 4.96V. But, upping to 12V (bridged from the red 12V lead) made no difference when the CMP=50 command was given.

I personally suspect a compressor at this point as my ECU will not accept the 17.1 update plus I suspect this car may have been jumped from a running vehicle many times by its previous owner knowing the circumstances of its ownership. ECU’s do not take kindly to such current surges.

Comments?

 

 

[Jonny Retrofit]

@Russ Stein  if the enable is only 5V then this is an early system.    
 

When the CMP=50 command is issued the enable line (yellow) should go ‘high’ (5V in your case) and the speed line (green) should have a PWM signal on it.  
 

if the signals seem opposite to that (e.g. they go away when CMP=50) then set the compressor logic to Inverted (INV=1)
 

Other than that, the compressor needs a solid 12.6V or higher on the heavy red cables.   The engine must be running or that voltage will dip immediately causing  no start.  

As you have the ECU connection working now, send a trace in the DIAG mode - capture the compressor start sequence. 
 

 

 

 

[Russ Stein]

Here is a trace in DIAG mode, engine at idle, blower in the car at half speed, condenser fan on, compressor still not on.. Trace taken after idling about 10-15 minutes. Blue LED bright blue, orange and red leads to compressor reading 12.52 volts; as noted I merged red and yellow to deliver 12v to the orange lead. I think I stated that the contractor is deleted on this installation.

[Russ Stein]

Jonny,

From this DIAG stream do you see a clue as still no compressor function? This one is being a bit stubborn!

 

 

[Russ Stein]

I want to close this thread as now fixed. Referring back to my post of July 2nd and my suspicion that this vehicle had sustained a voltage surge via jump starting from a running vehicle; this is confirmed by the attached image of the ecu’s charring adjacent to the hi-amp cable attach points. Fitting a new ECU-compressor immediately gave me functional A/C.