After dismantle the non factory Bosch alarmsystem on my 87 project, it was time to check if i could get the car started, but with no such luck. My diagnose it that the little wire on the starter is not getting 12V when I turn the key all the way. I get 12V on the relay, so I figure the problem must be somewhere from the fusebox to the starter.

Does anyone have an electrical schmatic of the route Iam talking about ?
and
if any has an idea where this route actually is going.

 

The wiring for this spans 2-3 pages. You can order a CD set of the diagrams from Roger (ROG100 here)as part of the workshop manual CD set. In the meanwhile, this circuit description assumes you have an automatic transmission:

Circuit for the starter relay (position XIV in the central electrics panel passenger floorboards) coil goes from the ignition switch (circuit 50)(yellow) through CE panel terminal A23, to relay socket coil terminal 86. That coil circuit continues out through relay socket terminal 85, out of the CE panel at U23 (brown/yellow) to connector T51 (in the spare tire well) (changes to violet/white) and to the combination neutral safety switch/backup light switch/gear selector indicator switch (on the left side of the transmission), back to T51 (violet), and from T51 (brown) to the adjacent ground point MP VI.

The supply to the starter solenoid gets unfused battery power (circuit 30) to relay terminal 30, out through relay terminal 87 to CE panel connector U13 (yellow) to the connector T18, which is the 14-pin connector near the jump post, right forward fender wall under the hood. From that connector the circuit continues through the front-of-engine harness, looping rear over the right-side cam drive, under the same cam drive forward, then across the front of the engine at the center lift bracket. The harness passes back under the left side cam drive to the alternator, then over the crossmember and down to terminal 50, the smalller connection at the starter solenoid.

Testing at the relay socket (relay removed), meter set for DC volts and grounded on one side, you should see battery voltage at terminal 30. You should see nothing at relay terminal 86, until you turn the key to start position, when you should see battery voltage confirming a good connection from the ignition switch. Change the meter to read resistance (Ohms), and you should see a very low number (virtually zero Ohms) at relay terminal 85 with the gear selector in park or neutral position, infinite in all other positions. You should see a low number at (a few Ohms) at relay terminal 86, confirming continuity through the solenoid coil on the starter.

The horn relay is the same type as the starter relay, so you can swap that one into the starter relay position if you suspect the relay is bad.

You should be able to hear the starter relay click as you cycle the key to start position.


Hope this helps!

 

Is the car an auto? if so you have a starter safety cutout that requires the transmission to be in park for starting. This is implemented using a transmission switch to ground on the 85 connection of the starter relay. Circuit is ignition switch to starter coil 86 terminal - coil - 85 terminal wired to connector in spare tire well*, onward to transmission switch.

*in notch above battery box and forward (wrt car) of the spare (under plastic cover).

Depending on where you saw 12v at the relay (on terminal 86?) you may have a coil activation problem based on the transmission switch.

Alan

Ahh saw Dr Bob had already replied - thats what happens when you get breakfast between starting and finishing a reply!

 

I must say Iam impressed by your knowhow :-) Now I just have to try to understand what you mean as to my known referance poinst.

As of the "which is the 14-pin connector near the jump post, right forward fender wall under the hood". That connector would be nice to have a more exact location or a picture. :-)


My 928 is an auto.

Alan: Are these the connectors you refer to ?



I do get 12v on pole 87 when turning the key, but no reaction on the starter. As I turn the ignition I hear and do notice the impact on the starter relay, which I immediately concluded that this is probably not a
relayproblem.

 

Open the hood. On the right front corner (passenger side on US cars, 'right' is right side looking from th erear of the car, can be confusing if you are facing the wrong way as you think of 'right'), at the top of the bulkhead (fender wall) between engine bay and the fender immediately forward of the radiator, there's a plastic rain cover with a (originally blue) screw-on cover/cap that shields the jump-start post. Blue post cover unscrews, plastic shield comes off. Immediately adjacent to that is the 14-pin connector. The wire to the solenoid is the yellow one in the harness, passing through pin 14 of that connector. Bottom of that connector is the car side, top is the engine side.

I'm not where the car is so I can't share a picture.

 

Yes that is the correct area: The wires in question are Violet, Violet/White on one side of the connector and Brown, Brown/Yellow on the other side (respectively).

However as you note if the relay clicks and you have power on the 87 terminal of the relay - that isn't the problem.





14 Pin connector is right next to the thick 'brown' (was once red) wire.

Alan

 

Success. Just found a connection from the relay to the starter. The project is back on track.
Thanks a lot for the help.

Now I need to find out what this contact is doing right under the fusebox. Any idea ?




Additional, I also would like to know if the injector on the right (blue) is a gonner. I can not see any pins sticking up, as it does on the left one( yellow)

 

The connector you show is used on non-cat cars to adjust CO. There's a small potentiometer that fits there for the task. Adding one to car with the US coding plug installed does nothing. So no need to worry about the connector.

One of our injector experts will share an answer on your second question.

 

from the injector picture it appears that the pintle cap is loose or not pressed on fully,
the wrong O ring may have been used as it appears to be fatter