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I have the interior of my 88 944 (base) apart right now so I figured it was time to diagnose why the radio and accessories (clock, cigarette lighter) won't turn off when the key is removed.
I understand theres some sort of circuit in the ignition switch, but I'm having trouble understanding it from the wiring diagram point of view.
Also I want to make sure the ignition switch is compatible. Removing it I find I have 928 613 017 01 installed. The PET calls for 964 613 012 00. I suspect it has something to do with this, however at a glance they appear functionally identical from the outside (same cross for turning, same markings on the pins).
Before dumping more cash into this as an experiment I'd like to confirm that these are indeed not compatible.
I'm also not ruling out the previous owner doing something to the wiring as the radio swap was a real hack job and he drilled a hole into the tunnel to run wire to the fuel pump and installed a switch bypassing the DME relay.
Have you tested the existing ignition switch to confirm whether its bad or not? Start there before making assumptions around whether its the correct part or not. If the ignition switch tests bad, then youll know you need to replace the switch. Im guessing you have a bad switch.
https://www.clarks-garage.com/shop-manual/elect-17.htm -this outlines how to test the starting portion of the switch, contacts 30/50 but you should be able to test the other contacts using a similar method, mainly you should not be getting any power between any contacts and ground when ignition switch is turned to the off position, or zero position in your wiring diagram. R position seems to indicate accessory on position, 1 is run, and 2/contact 50 is starting/cranking. 30 appears to be ground (or maybe its power and the other contacts are ground). With the ignition off, there should be no voltage between contact 30 or any of the other contacts. If there is the switch is bad. I cant guarantee my understanding of the above is correct, but just looking at the wiring diagram and reading through clarks, that is my interpretation - perhaps others will chime in who have done this before (Ive never had an ignition switch issue, so havent done this test personally).
30 is battery power. P is for parking light circuit (on in key remove position.) X is high current accessories, on in accessory and run, but not start. 15 is on in run and start (runs the engine stuff like DME.) 50 is starter, on in start. R is on everywhere but key remove position. You should have continuity from 30 to the other pins in their on positions.
So the testing got me thinking, theres a small connector to the side of the ignition cylinder on the housing. This appears to be the key removal circuit. Hooked my Ohm Meter to the pins. No circuit until the key rotates all the way like I'm starting the car, then stays on until I pull the key out. This makes me think the relay must have failed closed. I'll pull that next and investigate.
The windows also won't roll down if the key is put back into off but before being removed (before the door is opened) so I think theres definitely some wiring issues around the convenience features.
The windows also won't roll down if the key is put back into off but before being removed (before the door is opened) so I think theres definitely some wiring issues around the convenience features.
Normal operation according to the '87 owner's manual I downloaded. I know you have an '88, but I don't have a copy for that year.
Does the door switch work properly? In some I think the accessory power stays on until the door is opened, but maybe not the radio and maybe not in an 88.
Yes all conductors measure correctly at the proper setting on the switch.
Does your radio continue to operate with the switch removed like someone rewired the car in the past? The schematic notes that the radio is powered by terminal R, which you have confirmed is not connected to 30 with the key in the remove position. The switch may also be intermittently failing.
Also, I looked up the 928 switch number you gave. It is superseded by a new part number that indicated it is used by all 928s, late 944s and some 911s, meaning they all used the same switch back in the day.
Thank you for confirming that, I was having issues finding any reference to that part.
I was digging through my owners manual PDF and the windows should definitely roll down if I don't open the door. So more diagnosis will be needed. Battery is currently fried so my guess is theres a short someplace, however the door switches definitely work, tested via the lights in the front and hatch and the key inserted dinger.
Check the power window relay to see if a previous owner swapped out the correct 944 615 116 00 relay (5-pins with electronics in it to perform the hold on function) for a generic 4=pin relay. Oddly, the 85-88 parts list does not indicated a different relay for the earlier cars, which means that they should work this way as well. The '87 owners manual doesn't mention it.
Check the power window relay to see if a previous owner swapped out the correct 944 615 116 00 relay (5-pins with electronics in it to perform the hold on function) for a generic 4=pin relay. Oddly, the 85-88 parts list does not indicated a different relay for the earlier cars, which means that they should work this way as well. The '87 owners manual doesn't mention it.
I have confirmed the correct part number on the relay. The odd thing is I swear I heard it click when I put it back in. The battery was pulled at that point (as it was pretty dead, I took it out to maintain it and see if it needs replacing).
When I get electricity back in the car I'll continue with testing. Hopefully later today.
04-24-2024, 12:35 PM
Radio/Accessories won't turn off
