Kevin in Atlanta

Here's what the Commando instructions say:



Horn/chirp does sounds off. Off to see if I missed a step somewhere.

Later.

Kevin in Atlanta

Got the horn working. Next stop hatch.

Kevin in Atlanta

Diodes/Rectifier are very hot to the touch.

Is this correct?

Kevin in Atlanta

I believe that all the connections are proper. I press the trunk release and get nothing. If I pull the diver side hatch release I can hear the relay click.

I did deviate a little bit from the GTS diagram. I disconnected the wire at the hatch pull and added a female clip to the new wire and connected it to the pull switch. On the other end I ran it to the Hatch Disarm on the Alram. I then connected the KE's Hatch (-) to that wire with a tap con. I also connected the 85 from the Hatch relay to that same wire with another tap con.

Any help would be appreciated.

I will take a lot of pictures once all this works.

Alan

Understand that their diagram for the hatch release will not work for your 928 - they have no conception of how a 928 is wired and it isn't like any other vehicle.

Your diodes should never get hot - if they do it means you have them connected incorrrectly (probably backwards).

The rear hatch will never work unless you modifiy the stock wiring to create a ground path (somehow) when the doors are closed. I showed an example of how to do that - there are several other possible ways.

If you don't do this your hatch release will only work when a door is open (not just unlocked - actually open) - check and see if this is the case. Obviously this is not very useful...

Alan

Kevin in Atlanta

Alan, I used your diagram. The brown/white wire has been cut and grounded to the body, the yellow from the hatch release connects to the other end of the switched ground (brown/white) per your diagram.

The diodes (6a) are as printed with the bar end (-) pointed toward the alarm unit. If they weren't would the turn signal lights blink?

dprantl

I don't know about the trunk release, but my diodes get hot in the GT and also got hot in my former '86 as well.

Dan
'91 928GT S/C 475hp/460lb.ft

Kevin in Atlanta

Thank you, that helps.

Bill Ball

I had another idea for how to wire the keyless remote hatch release. Should retain all stock functionality of the hatch release pulls (only work with door open). Also, in cars with dual hatch pulls (i.e., pre-GTS) you would not need any wires running across the car from one pull to the other and would only have to interface the keyless system with one of the pulls. The hatch pulls otherwise stay wired as stock. Alternatively, you can interface with the yellow wire at S11 on the CE panel on GTS's or connector T19 near the CE panel on most earlier cars and leave the pulls alone. The diodes in the hatch release circuit isolate the keyless ground from the door pin switched ground.

Alan, tell me why this won't work. Note to everyone else - this drawing is hacked from Alan's original work.

[EDIT: SEE CORRECTED VERSIONS IN POST #46 BELOW. Note Alan's comment that a relay or transistor is needed on the output from the remote hatch release sionce it is not rated for more than 200-300ma in most keyless entry systems.]

Alan

Bill - Conceptually this should work well. I like your idea - the only thing not to like is the installation of the 2 diodes in the tool panel/hatch release area (just in terms of making it tidy and robust), and of course while a single wire must still be wired forward to the controller - it does cut down on wiring across the car for a dual release model.

However I'm not sure that typical KE units can sink enough current on the Aux/Hatch output to support the relay coil current and the motor current concurrently. The motor is a very light duty item (<<1A) but still may be too much for some units... see what the current drive specs are on this output?

Another possibility would be to replace the diode for this with a transistor 9at the rear hatch motor) to provide some current amplification to alleviate this issue - not much more complicated...? Of course another relay is also an option...

You also could just try this out - but I'd check the specs and the motor current when operating first - if you overload this output it may work initially - but create a long term reliablity issue.

For me the wiring wasn't a very big deal - I already have lots of extra wiring bundles to various places in the car so was able to use these.

Alan

Alan

OK I guess the turn signal confirmation diodes may get hot when operating (lock/unlock etc repeatedly) depending on their size. Mine are very big and probably wouldn't be noticeably hot unless I continued activation for a while (never tried itz) - just due to their themal inertia. Smaller diodes will have less thermal inertia and a higher on resistance so will heat up more and faster (mine are ~40A stud mount diodes).

Alan

Bill Ball

Alan: I'm using an old Audiovox APS-45, and your warning is appropriate - the channel 2 negative output I would use is rated at only 300ma, and they caution against using it to directly drive anything but a relay - I missed that! I'll revise the schematic. THANKS!!

Alan

Bill maybe like this:

Alan

Bill Ball

Alan:

WOW! That is great. What value do you think Rx should be? Can you give me a common transistor part number I might pick up at Fry's?

Hey, one other thing... I did not use a horn relay but hooked the remote's horn ground output to the wire that goes to pin 85 on the horn relay, which is a BR/WT wire at H22 on the CE panel in my 89. It would be N15 in your GTS. Seems to have worked fine for year. So, I could get this down to one relay.

Alan

Bill - I updated the diagram - I had missed off 1 extra diode that is required.

The base resistor can be approx 600-1K ohms and you need a transistor rated for approx 1A min continuous. I'd plan to mount the transistor and diode in a little project box on a PCB - so a TO-220 style transistor would be easy to mount and comes in appropriate ranges. You need a silicon NPN with a gain of at least 40 - I don't know what Frys carries but you should find some like this easily enough. the TIP47 - TIP50 series by motorola should work fine.

Alan