850 sedan trunk lock testing question.

Teddy1975 · Post by **Teddy1975** » 12 Jul 2016, 02:14

Less than one (1) amp is needed as the motor is really small. If you have a small power supply, then use this instead of a car battery. If you only have a car battery, make sure to put a small fuse (5A or smaller) on the live wire to prevent damage done to the wire harness and/or central locking relay.

: fused.png (6.17 KiB) Viewed 751 times

Caution: Do NOT put any voltage on the wires while they are plugged into the harness. Terminal 6 and 7 are short circuited when plugged in and the central locking system isn't operating the door locks. This is intended.

To test it, use this table:

Action	+12v (live)	Ground (negative)
Lock	Term #6, YEL-BRN	Term #7, YEL
Unlock	Term #7, YEL	Term #6, YEL-BRN

Don't keep power on the motor for a longer period than a second or so. There is a small risk of overheating the wiring inside the motor, which will render it useless.

If you pay attention to the cautions, this is quite easy to do with no risks involved.

Post by **scot850** » 12 Jul 2016, 08:26

I will use my 2A trickle charger and just touch the pin to see if there is any movement. Warning is noted!

Thanks again.

Neil.

Teddy1975 · Post by **Teddy1975** » 14 Jul 2016, 20:54

Hi Neil.

Did you have any luck with the lock?

Post by **scot850** » 14 Jul 2016, 23:09

No, none at all, and neither with the fuel flap lock. Both appear dead. I have pulled a bunch of fuel flap locks at a junkyard and plan to try them tomorrow, along with a couple of trunk locks (most of the 96- Volvos were wagons so not much choice). I'm hoping that one of each will be good when plugged in so I can verify the problem is the electric motors and not the wiring or something else.

I plan to do that tomorrow and I'll let you know how that goes.

Neil.

Post by **scot850** » 15 Jul 2016, 17:39

Although I can't be 100% sure yet, I may have found the source of the problem. After trying 2 more motors with no luck (my view is surely 3 motors can't all be bad) was to check the wiring. I removed the cover that runs up the trunk hinge and cut the plastic (fibreglass?) sheathing (and it cut my finger, bugger that stuff is sharp!!), and no obvious broken wires at the point where the wires leave the plastic cover. I pulled the back mesh sheathing back lower and found 3 broken wires loose in my hand. Just what I love, repairing hard to access wiring with sausage fingers! So I will have to make up a short pig tail and solder it in.

The fuel tank lock was just a (an expensive) dud motor. I pulled 7 ($5 CDN each rather than $135 CDN from the dealer) and 4/7 were good. 1 of the 7 was from a S70 and looks physically the same, but when connected it un-locks then re-locks itself. Weird. Hoping to see if they were also compatible. It may of course be the motor itself, but I don't plan to pull the 'R' apart to prove it! Maybe P80 fuel locks work differently?

Neil.

Post by **scot850** » 17 Jul 2016, 22:57

Was busy this weekend and so only had a half hour tonight to look at the wiring. I just used wiring marrettes to temporarily re-connect the 4(!) broken wires to see what happens. Good news is the lock assembly works fine as did the 2 spares I got from PnP. Not sure about keeping the spares as I will not have a need for them, but torn as I know if I return them good parts will likely just get junked.

I'll have to take a run back to PnP and look at pulling the trunk harness from a car to give the correct wiring colors to fix the loom. Hopefully good for another 20 years!

It would appear that using my trickle charger to try to test the motor on the trunk latch didn't work. May have try my regular charger on 2A to see if it is how the trickle charger works that it won't make the motor work even when just trying to 'dab' the connections.

Neil.

Teddy1975 · Post by **Teddy1975** » 20 Jul 2016, 13:35

Or use the car battery. Just make sure to have a 2A or 5A fuse inline.

Battery chargers, especially the "intelligent" ones can fluctuate quite a lot in both power and voltage and need the bigger load of a battery to really work.

I use a small variable lab powersupply that has an output from 0-30 volts DC at max 3A for testing stuff like electro motors, LEDs, bulbs and other electronics.

Post by **scot850** » 20 Jul 2016, 19:45

Having a lab variable voltage supply would be handy! Either way I bought a bunch of used parts from Pick and Pull and found the fuel flap motor was junk, and the wiring harness for the trunk lock had 4 broken wires at the hinge. I temporarily reconnected them and the motor (and the 2 spares I pulled) were all fine. Now have to repair the harness.

Thanks for the input and help. Really appreciated.

Neil.

850 sedan trunk lock testing question.

Re: 850 sedan trunk lock testing question.