jwillman

So I just finsihed up refreshing all the vacuum lines, removed , cleaned and reinstalled the throttle body and finished the rest of the ground points.

I put in a new fuel relay and got the car started after several attempts. Still running a bit rough and does not respond consistantly to throttle so next steps are check timing and then start trouble shooting CIS pressures.

One odd think is that the headlights work with the ignition on and engine not running. If the engine is running the parking lights work but the headlights will not raise or illuminated. If I turn the headlights on first and then start the car the headlights go out but stay in the up position.

is this a known / common issue? Any suggestions. Looking at the wiring diagram the ignition switch is in the headlight system but not sure what I could check.

Thanks

pcar928fan

Hmmm...can't help you Jim...hope someone will step up w/ a thought on this one...

jwillman

Looking at the wiring diagrams today it looks like the only "engine on" related component is the ignition switch. Wiring diagram is a bit confusing and I can't figure out what positins in the switch drive waht actions.

Anyone run into this before?

Thanks

Mike B

Jim, I can't help you with specific knowledge about your '79 but I did have issues with my '88 headlights. I had similar issues after I replaced the engine...the headlights were fine before she sat for awhile.

To cut to the chase...I ordered a new relay with no joy. The problem turned out to be the original headlight switch. I have no idea why it failed but I replaced it with a good used one and all is well. I'm not sure if this will help but I thought I would pass it on.

jwillman

Thanks Mike. I had discounted the headlight switch as it functions properly when the engine is not running but I will takje another look at the wiring diagram to see if there might be a way for this to happen.

WallyP

The headlights should go off when you turn the ignition switch off, so it sounds as if something isn't right on that circuit. The only circuit that I can see looks like the connection from the X bus to Terminal A in the socket of Relay IV. Pull Relay IV and check for power on Terminal A with the switch on, and then with the engine running. You should have power both times.

If you do, the problem may be with Relay IV. If you don't, the problem may be with the X bus, which is powered from Terminal X on the ignition switch.

jwillman

Thanks Wally.

I did some reading in the owners manual and then did another round of testing to lay out exactly what works and what does not.

Owners manul calls out an interupt during starting for headlights. What component provides that function?

Thanks for the help.

jwillman

Upon further review there seems to be a difference between the wiring diagram I have and the relay table which agrees with the owners manual. Table/owners manual lists "headlight safety relay" as being relay# XVI.

The wiring diagram I have shows it as realy #IV. I reinstalled relays per the table / owners manual 2 weeks ago after fuse panel refresh but had never had engine running and done the headlights test prior so do I have relays switched or the wrong wiring diagram?

Is there somewhere that outlines functionality of the relays? Would be great to understand what they are suppose to do!

Alan

Always photograph the actual relay locations before you disassemble a panel - if need be mark them appropriately on the can top (sticker?) to be sure you know which is which for those that are different (e.g. non ...53 types)

Alan

Alan

I would tend to believe the Wiring Diagram - its a Porsche document !

To be sure see that the Safety Relay with the extra pin "A" should go in the socket with that pin actually wired. If a connector is in the socket its wired - you can tell from the front.

I suspect that pin A on socket IV is wired and "Pin A" on Socket XVI is not.

I think the 78/79 relay chart just swaps the text for relays XVI and IV - they aren' the same t - they are functionally very different... According to the wiring diagrams the relay for XVI should be a standard DPDT Bosch relay prob the same type as Relay III - (and it is in the chart).

Alan

jwillman

Thanks Alan. The relays were already marked but I have learned to not assume the po/s did it correctly which is why I confirmed by PN as well.

I checked the relays against the socket wiring and wiring diagram and they marry up on all respects.

jwillman

Thanks Wally.

The headlights do go out when the ignition switch is turned off. All functionality is per the owners manual except the lights do not come back on after the starter switch is released once the engine is started.

I'll check the voltages next time around!

Mrmerlin

check the headlight relay for the correct part number and if it is correct then open it and clean the internal contacts you may find one or more of them burned.
Also check the headlight connectors for corrosion and the grounds for the headlights

Arena996

Just a thought, is your ignition switch returning back after starting. I had a similar situation a couple times and it turned out the key was rubbing the dash pod around the ignition. giving it just a slight turn backwards allowed the switch to sit properly at the number 2 position (number 3 being start). Give it a try it doesn't cost anything.
JIM

jwillman

JIM and All,

JIM wins the prize. I started the car again toady after getting the clutch and brake hydrualics reinstalled and sure enough the ignition switch is not returning completely to the #2 position. I assit it a bit and then the headlights function normally with the engine running.

I am now obviously concerned about the ignition switch. I assume there is likely a spring for the return function. Is this something that can be taken apart and cleaned up or the spring refreshed or am I better off replacing?

Thanks again all for the advice!!!