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Central locking problem on Primera 2.0 eGT

I have a '94 Primera with a central locking problem. Basically it doesn't work. I've checked the driver's door and the switch is working.

I've checked the central locking timer in the driver's footwell, and as far as I can tell, it's working OK - it clicks when the door switch is closed/unclosed, and basically connects the +12v for about a second to the timer outputs - connected one way for lock, the other for unlock.

I've tried manually connecting the +12v and 0v inputs to the timer directly to the wiring that should be going from the timer to the door solenoids - but nothing happens. I've recently had this car from my Dad, who had it laid up for a few months (though it was run regularly). I believe that the problems started during that period. It does seem unlikely that 3 solenoids would go wrong at the same time (there is NO sound from any of them) so I am wondering if it's a wiring problem after the timer but before the first solenoid.

All that comes out of the driver's door is the two leads from the lock switch to the timer. I am guessing that the outputs from the timer to the solenoids must go independently to each door, but it's impossible to see where the timer output goes as the wiring disappears into a large cable loom. I was kind of hoping that the next logical thing to investigate would be the passenger door, but this might not be the case if the wiring doesn't next go there.

Does anyone have any suggestions as to how I can progress the fault-finding here? Regards Phil

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Is there a childlock switch that's been pressed by mistake?

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SteveB

Thanks for the suggestion - but it wasn't that (I did go and check though!) I should have added that I measured the resistance across the pair of wires that should go to the solenoids, and it was quite high - around 300Kohm if I recall rightly. Not open circuit, but probably higher than one would expect from 3 solenoid coils in parallel?

SteveB wrote:

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You would expect only a few ohms or tens of ohms for the solenoid as a few amps would be needed, but I've looked at my old Haynes manual circuit (I used to have a P10) and there's 2 diodes in the solenoid circuit which may effect readings on a meter, it will depend on the meter type. Most meters will read much higher than the real resistance. It can be best to check such circuits continuity with a small (3 volt or more) battery and low power bulb as the diode's effect is negligible then apart from it being polarity conscious (try the battery both ways round).

In fact, even though my trade is electronics, the circuit doesn't make a lot of sense as it couldn't work at all as shown. I reckon the 2 diodes common connection must go to ground in the door for it to work, dunno for sure. The diodes are there to allow current to flow in either direction in the solenoid for locking /unlocking. As none of your doors are working it can't be the actual solenoids at fault. If there is a childlock I would suspect that as being open circuit from non-use as I had a few switches pack up on me on my P10 and it was always the ones that never got used that failed. I managed to strip a fog light switch and fix it (it just needed the contacts wiped clean even though they looked like new), springs and ball bearings flew everywhere LOL. Good luck.

Reply to
SteveB

Thanks for your suggestions re. testing the diode circuit, I'll give it a go. (I'd also stared at that diode circuit and given up trying to work out how any current would flow with the circuit as printed!)

I guess I hadn't considered that the child locks would have an electrical as well as a mechanical action. I assume that they are the switches shown in the Haynes manual in each door lock actuator circuit (despite the fact that the passenger door doesn't have a child lock). The only problem with that theory is that unless they were all broken,I would have expected maybe some doors to work (assuming that the passenger door really doesn't have a child-lock switch buried somewhere).

I'm also puzzled by the diagram in the Haynes manual for the 'Lock/unlock switch' (ie driver's door). In my version of the manual there's three components with the same reference number - the basic door lock switch with 2 contacts, and two versions (one for electric windows, one without) of what seems to be more circuits switched by this component - yet as far as I can tell there's just the two wires from the main key-operated lock switch, although more wires go to the timer. Not sure where the others come from! This may be a red herring of course.

I suspect what I'll have to do to progress things further is to have a look at the passenger door; if I can manually wire the solenoid into the timer (or just momentarily connect 0/12v) and it works, that will at least show me if there's a fault in the wiring after the timer but before it splits for the individual door circuits. . Mind you even if that's the case, by-passing the wiring loom to fix the problem might just be difficult!

Thanks for your help Phil

SteveB wrote:

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You stated that you get +12v on the output connections from the timer ( term

2 Lt green and term 4 Lt green/black) but did you get -12v on the opposite lead as when it locks you get +12v on the lt green and -12v on the lt green/black and when you unlock this is reversed -12v on the lt green and +12v on the lt green/black, this is the only -12v feed to the solenoids.

Trevor Smith Primera 1600 P10

Reply to
Trevor Smith

Hi Trevor - I did check that the polarity on the leads you mention changes as you go through the lock/unlock process. I didn't measure the voltage with respect to earth, but the difference between the two leads, so whether it's really -12v or 0v I am not sure - I think from the circuit that changing which lead is +12v will be sufficient (given the diodes in the solenoid circuit) to change the direction that current flows in the solenoid, and hence it's direction of travel. The timer module itself just has a couple of relays in it, and as far as I can work out just swaps around the 0v and 12v levels to either of the wires you mention, as you lock and unlock.

The fact that I dont' get any action (or sound of attempted action!) when I directly connect the 0 & 12v supply (as at pins 1 & 3 of the timer) to the outputs at pins 2 & 4 suggests to me that there is a fault in that output wiring somewhere. I did try connecting the supply both ways round with no difference in effect. Thanks for your thoughts Phil

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