mystert

My 92 964 C2 has a 993 CCU installed in it. Im trying to figure out why my oil cooler fan doesnt work and everything has tested OK and Im down to the CCU being the culprit. I dont have pins 1& 19 jumpered. Think I need to do that to get the fans working but first I want to ID the unit. I have the face plate off and can look inside at the circuit boards. On the outside it just has a sticker from LA Distmantlers and "993 good @ 10/12/06" written on it in sharpie, but not other ID marks.

Where is the part number located on this thing? The fan on the back has a 964 number in it but the unit has the two snowflake buttons on the left.

Thanks

Partisan

Eric,
the G1/G19-bridge is not necessary for the oil cooler to run. This is for the feedback-signal coming from left and right auxiliary blower in the motor compartment. Anyway, in case there is no G1/G19 bridge in the wiring, you should add it. Easy task when the CCU is out and opened, and you have a soldering iron.

The oil cooler blower is activated by applying ground level to pin K10 for stage 1, and K22 for stage 2.
The temp sensor is routed to pin G12 and G18 (G18 is the common sensor ground).
The reading should be about 6kOhm at 25°C. Below 700Ohms stage 1 is activated.

The oil cooler activation inside the CCU failes very rarely. In most cases the fault is in the car.

Regards,

Michael

mystert

Success! After jumping G1 to G19 as pictured, the low speed fan works automatically at 700ohms. When measuring the oil cooler fan switch resistance, it doesn't reach 700ohms and kick the low speed fan on until the temp gauge reads about 9:45 (see picture). From I've read, this seems a little high. Maybe my gauge is a little out of calibration? Or the oil temp sender is a little out of spec?

ToreB

Are you measuring the thermistor with the CCU connected? It should be measured with a ohmmeter connected to the car harness without the CCU.
The oil cooler fan speed treshold settings are a bit higher in the 993 CCU compared to the 964 version, and the operation you mention might be expected. See here for some details on this. The tresholds are set in software and cannot be changed.

Another reason for this could be that the thermistor sensor is located on the front oil cooler, and its operation rely on any circulation of oil in this part of the system. The mechanical oil thermostat controls the oil flow to the front cooler, and it could be that the thermostat opens at a bit higher temperature than expected. It is not uncommon to see problems with the oil thermostat.

Cheers,
Tore

mystert

I measured the thermistor resistance in three places to make sure the wiring was good. First I measured it directly at the sensor in wheel well with the plug disconnected, then at the female side of T34 connector in the frunk, then at the dash with the CCU removed. All three locations gave me the same 15.5k ohms at around 80F garage/room temp. I then warmed the car up and the resistance reading didn't begin to lower until after them thermostat had opened as expected. My thermostat opens up just above the third line from the bottom on the gauge, then quickly drops below the third line as expected. With the ohm meter probes in the connector attached to the car wiring harness and CCU disconnected and laying on the passenger seat, I watched the resistance get lower and lower and it finally reached 700 ohms at about the 9:45 mark as shown in the picture in my previous post. I shut the car off and plugged the CCU back in, started the car again and the fan began to work properly. The temperature would go slightly above the 9:45 mark and the fan would turn on at low speed. Then the temperature would go a bit below the same mark and shut off, then repeat.


I have read the pelican parts version of the P-car website before I started working on this. Most posts I have read show the low speed cooler fan turning on a bit lower than mine does. That is why I expected my sensor to be out of calibration range possibly. Without an accurate thermometer, its hard to exactly what temp the car is actually at

mystert

I got my T-OBD in the mail and got it working. Cleared all the AC codes and code 16, 31,32 come up. 31 and 32 are for the mixing flap servos. Not sure what code 16 is. Any ideas? Another issue I have is the condenser fan pulsating when I move the temperature switch off full cold. I've read on Tores site that a few wires need to be jumped etc to make it function properly but no detail on exactly what has to be done. Lastly, I can't find a part number on my CCU to identify it. I think I would need this to ensure the correct mods are done? Thanks for all the help so far.

Partisan

Error code 16 is the missing outside temperature sensor, which is only present in 993.
What version of CCU do you have? 993.659.047.00 or .01? xx.00 runs on software H05/06, xx.01 on H07/08
xx.01 can not be used in 964 cars without modifications.

Cheers,
Michael

mystert

I have no idea what version of the 993 CCU I have hence the post title "Help ID'ing CCU". It has no stickers or engravings regarding the part number on it. How do I tell if its a XX.00 or a XX.01? I am in the process of modifying the wiring per Tore's instructions. He really knows what hes talking about. Once I get it finished ill post the results. Im having trouble unsnapping the G connector to get the pins out. The K plug came apart easily but the G pin doesn't want to snap apart far enough to get the pins out. Do you have any tricks to disassemble the G connector? When I snap the one end out the other side snaps back together and vice versa. The K connector isn't as wide as the K connector and is easier to snap apart.

creaturecat

the connectors only swivel one way.
the G has the clip on the rhs of the ccu (when facing ccu, still connected).
pop the clip, with a small screwdriver. you may have to give a small pry along the connector to move it out of it's channel.
the wires are zip-tied below the dash. you really have to cut the zip ties to facilitate removal and reinstall.
a small shot of wd40 will help the connectors slide together more easily.

edit: never mind

i guess i misread the query.

Partisan

The CCU version can be read out via the OBD-interface. But it is quite clear that it must be a 993.659.047.01, since it's the only one that throws error 16.

I have never disassembled the connectors to get the contacts out, so can't give you any advice.

coguy

I also have a 1991 964 that has a late model 993 CCU (993 659 047 01) that the PO installed.

Any chance you could pass along the wiring modification instructions that Tore provided?

My research so far tells me that the tracks on PINs G7 and G9 need to be modified in order for this CCU to work in a 964.