My rear fan bypass box!
04-13-2012, 04:39 AM
#121
Just trying to understand the whole story:
Concerning the battery drain experienced by Twood:
'Some back ground - I have the heater bypass mod installed with the resistors in place but could not get the CCU to work other than on the blue (lowest setting)dot. Removing the relay and jumping the approriate contacts made everything work perfectly except that I had a battery drain and after 2 days would find I had a flat battery.'
If you do the jumper trick with the resistor replacing the blower or the rear blower connected, it will drain the battery (the battery will always feed the resistor - blower).
Question: With the jumper mod and blower/resistor disconnected, does it drain the battery (on a 89/90 model)?
Concerning the battery drain experienced by Twood:
'Some back ground - I have the heater bypass mod installed with the resistors in place but could not get the CCU to work other than on the blue (lowest setting)dot. Removing the relay and jumping the approriate contacts made everything work perfectly except that I had a battery drain and after 2 days would find I had a flat battery.'
If you do the jumper trick with the resistor replacing the blower or the rear blower connected, it will drain the battery (the battery will always feed the resistor - blower).
Question: With the jumper mod and blower/resistor disconnected, does it drain the battery (on a 89/90 model)?
04-13-2012, 12:03 PM
#122
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Location: Peachtree City, Ga
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The best trick is to install a relay that allows the connection when power is on - key in ignition - the relay completes the circuit while the car is running and then breaks the circuit once you shut the car off. This prevents the battery drain under any situation.
04-13-2012, 03:33 PM
#123
Rennlist Member
You do not need a relay, all you have to do is run a fused (7.5 amp) wire from the + side of the nearest coil to pin # 87 where the heater blower relay used to be, and you are done.
04-13-2012, 05:37 PM
#124
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Tried that on my car and as long as there was a direct connection I had battery drain, the relay was the only trick that stopped the battery drain. Have a 91 - don't know, but think a lot of this is car year specific. Glad that your solution works for you.
04-13-2012, 05:46 PM
#125
I think your battery drain cound be caused by something different.
Last edited by anto1150; 04-14-2012 at 04:03 AM. Reason: caused instead of caudes
04-13-2012, 08:03 PM
#126
Rennlist Member
04-13-2012, 10:53 PM
#127
Racer
Just trying to understand the whole story:
Concerning the battery drain experienced by Twood:
'Some back ground - I have the heater bypass mod installed with the resistors in place but could not get the CCU to work other than on the blue (lowest setting)dot. Removing the relay and jumping the approriate contacts made everything work perfectly except that I had a battery drain and after 2 days would find I had a flat battery.'
If you do the jumper trick with the resistor replacing the blower or the rear blower connected, it will drain the battery (the battery will always feed the resistor - blower).
Question: With the jumper mod and blower/resistor disconnected, does it drain the battery (on a 89/90 model)?
Concerning the battery drain experienced by Twood:
'Some back ground - I have the heater bypass mod installed with the resistors in place but could not get the CCU to work other than on the blue (lowest setting)dot. Removing the relay and jumping the approriate contacts made everything work perfectly except that I had a battery drain and after 2 days would find I had a flat battery.'
If you do the jumper trick with the resistor replacing the blower or the rear blower connected, it will drain the battery (the battery will always feed the resistor - blower).
Question: With the jumper mod and blower/resistor disconnected, does it drain the battery (on a 89/90 model)?
Mine drained the battery and I needed the relay. My 964 is a '91 model build in October '90
04-16-2012, 04:56 AM
#128
I am trying to understand why there could be a battery drain on a 90 or a 91 if the blower is disconnected and has NOT been replaced by a resistor.
Unless there is a path from input G19 of the Control-Unit to ground I do not understand (see wiring diagram at K-29).
But even so, to drain a battery, that would be a massive current in that input...
Gus and Twood: Did you have the blower OR the resistor replacing the blower connected when you had that drain?
(I don't want to modify my car, I just want to understand what is happening....)
Cheers.
Unless there is a path from input G19 of the Control-Unit to ground I do not understand (see wiring diagram at K-29).
But even so, to drain a battery, that would be a massive current in that input...
Gus and Twood: Did you have the blower OR the resistor replacing the blower connected when you had that drain?
(I don't want to modify my car, I just want to understand what is happening....)
Cheers.
04-16-2012, 05:18 AM
#129
Racer
Hi,
first remove the rear blower relay. Then install two jumpers in same place. Connect 30 to 87 and 30C to 87C, or 30 to 87C and 30C to 87. No difference. 30 and 30C are anyway connected.
No more. You can now remove temperature probe and original resistor too, if you want.
first remove the rear blower relay. Then install two jumpers in same place. Connect 30 to 87 and 30C to 87C, or 30 to 87C and 30C to 87. No difference. 30 and 30C are anyway connected.
No more. You can now remove temperature probe and original resistor too, if you want.
Sometimes I do no need to know why I exist but it good to believe I do exist.
Just trying to understand the whole story:
Concerning the battery drain experienced by Twood:
'Some back ground - I have the heater bypass mod installed with the resistors in place but could not get the CCU to work other than on the blue (lowest setting)dot. Removing the relay and jumping the approriate contacts made everything work perfectly except that I had a battery drain and after 2 days would find I had a flat battery.'
If you do the jumper trick with the resistor replacing the blower or the rear blower connected, it will drain the battery (the battery will always feed the resistor - blower).
Question: With the jumper mod and blower/resistor disconnected, does it drain the battery (on a 89/90 model)?
Concerning the battery drain experienced by Twood:
'Some back ground - I have the heater bypass mod installed with the resistors in place but could not get the CCU to work other than on the blue (lowest setting)dot. Removing the relay and jumping the approriate contacts made everything work perfectly except that I had a battery drain and after 2 days would find I had a flat battery.'
If you do the jumper trick with the resistor replacing the blower or the rear blower connected, it will drain the battery (the battery will always feed the resistor - blower).
Question: With the jumper mod and blower/resistor disconnected, does it drain the battery (on a 89/90 model)?
09-26-2012, 01:46 AM
#131
Racer
has anyone kept thier original piping and done the jumper whilst disconnecting the blower and resistor and how did that turn out ? thinking of doing this but dont have time or money to get into new piping just yet. thanks in advance for any replies.
09-26-2012, 09:48 AM
#133
Racer
think im gonna try this out as I put a new/used relay in and it had heat and air right afterwards until i cranked the car again several hours later then absolutely nothing.
09-26-2012, 02:28 PM
#134
Racer
ok spent a few hours on it today...did the set up as in post 123 pic i think as it was the easiest to try and seemed the safest for my experience level. finally, no go on my end of it. good thing fall is here and its not so cold that i need heat and i can still put the top down if its warm enough out. this one may go to a repair shop this time. so far ive been 2/3 of projects on average. thanks for the posts on this and at least i can say that i gave it a shot before shop time.
09-26-2012, 04:11 PM
#135
Drifting
Thread Starter
What do you mean with "no go". Doesn't the heat or fans work as they should? If you tried to run the fans or heat before you did this the error codes in the CCU has kicked in and you need a diagnostic tool to reset it. Otherwise it wont work even if your connections are done in the same way as in post 123. Try to reset the CCU before you do anything else.
Best
Thomas
Best
Thomas