Door unlock problems
I have problems with unlocking the car. Little history, we have a 2000 Toyota BB and a 2006 Scion XB (spare parts car). I have been swapping parts over from the XB onto the BB. The latest swap is the rear trunk lid. The problem was that the BB is mechanically opened, while the XB is electrical. I had to rewire the whole door control unit (relay), because the BB has less wires going to it.
Finally, I got it all done and working. But the unlock system is not always working. The problem is that it will not unlock when you use the remote or the unlock buttons on the door. You have to use a key to get in (does mechanically unlock). Unlock no problem. Other problem is that when you start the car and you want to lock the doors, it will lock and instantly unlock again. After the car is turned off, the car will lock and unlock normally for a while. Then the problem starts again.
Yes, I have tried a different unit, still the same problem. BTW, they are very expensive in Europe (600 euro, about $800).
So, I have been measuring the in- and outputs of the door control unit. As far as I know, the inputs work normally. But, there isn't any voltage at wire D4-3 (L-B) or D4-11 (Y-G) when the problem happens. That's the door lock motor unlock drive output. The only thing that I noticed is that the current from the door switch (all other then driverside) doesn't go below 1 ohm when doors are opened. This is at pin D4-7 (R-W).
This will work normally after the car has been started, but only last a short time.
Any idea what might be the cause of these problems? Need the know soon. The car has to go through yearly inspection.
Sorry for the long text. Thanks for the help.