1989 928s4, when ignition switch is turned, dash lights up and all electrics work. But no sounds from anything trying to engage. No clicks or anything. Car ran fine yesterday. New starter installed 6 months ago, checked all fuses, and swapped out relays with spares. Cleaned battery post and cables. Nada. ECU/EZK?

 

Starter goes... Or not? Fuel pump buzzing?

 

NOTE before you clean anything , take a battery cable and attach the cable to the negative battery terminal then attach the other end to the strut anchor nut ,
try to start the engine if it starts then your ground cable needs to be swapped out.

So first reclean all of the the battery connections.
Inspect the ground cable for white powder where the cable fits to the chassis .

If this doesn't work then replace the starter relay with the horn relay try to start.

Put the trans in neutral and try to start if its an automatic.

If no good then make a jumper wire connect one side to the hot post and touch the hot wire to the engine side of the 14 pin connector where the starter wire is,
this should turn the engine over without the key .

NOTE make sure the transmission is in neutral if you have a 5 speed and park if auto.

 

I see a little white powder around the nut and strap to the chassis. Will address it first thing.

 

Nothing. Dash lights up, horn honks, windows work, headlights etc.

 

The fuel pump doesn't energize without a signal from the CPS (via the EZ-K and LH). The crank position sensor (CPS) doesn't give a signal unless the engine is turning.

I'd pull and replace the starter relay with the one from the horn, as you've already said the Horn works. (they both use the same type of relay).

I'd also clean the grounds - it never hurts and you've already said you have white corrosion.

 

Throwing in the towel. Towing it to the shop.

 

It could be that your new starter motor shaft did not retract all the way back into the starter. If that happens, the starter motor will not spin.

This happened to me twice. The first car was an ongoing epic detective saga involving intermittant symptoms, alarm systems, closing and opening doors/hatches and hoods in the correct order, locking and unlocking doors/hatches, etc. The second car was not intermittant but flat out non-functional and pointed me in the correct direction to figure out the problem with the first car. Both cars had starters with manufacturers grease on the starter shaft that collected dirt and grime and did not allow the starter motor shaft to retract fully and the solenoid to kick the starter on.

 

Have you had/done any recent work on the car ?
I ask for I had the same symptoms after I removed the intake - had my teenage son as my sous chef - he didn't torque a bolt that goes into the water jacket on the R side of the engine which held down the FPR bracket - this caused a coolant leak that collected in the 'V' affecting the deep ground points which ground the engine controllers - had electricity but absolutely nothing when I turned they - as part of the hunt for the cause (I had the engine running 10 mins before the failure) I looked into the 'V' under the manifold and saw a lake down there - then I tracked it back to my sous chef's torquing abilities.

 

It was the starter. Even tho it's new and not rebuilt. The solenoid was sticking. A few taps with a mallet..and it started. Replaced it right away.