jwbeck17

I'm going though some electrical and starting issues and noticed that after I cleaned many of the grounds that the digital dash no longer lights up when I unlock the door or connect the ground strap. It turns on when I turn the key. Has anyone seen this before?

davek9

Is fuse #24 good and are the fuses all clean?
I'm not clear on " when I unlock the doors..", the interior lights are on the same circuit, do they all work?

jwbeck17

Fuse 24 is new, in good shape, as well as the others.

When I unlock the doors, or open them, Usually the interior lights illuminate as well as the digital dash, showing the milage on the left, the avg mpg in the middle, and the triptometer on the right. The cabin lights illuminate correctly when the door is unlocked and opened. However the dash does not light until the key is inserted.

Alan

Why would you think that is normal behavior?

Yes every time - this is how it is supposed to work!

Alan

jwbeck17

This is a surprise to me, since I have had the car for 8 year and the digital dash part would always light up when either the door was opened or I reconnected the battery ground strap to the chassis mounting point. The screen would stay on along with the lights then shut off with the lights after a normal time. If the correct process is that the digital dash only lights up when the key is inserted and my ground cleaning fixed a gremlin, then I'm happy with knowing that.

I'm having some starting issues so I am checking out anything that seems different than before, hence my question.

jwbeck17

So based on the video, my battery fluctuates between 8.6V-9.7V during cranking. I suspect that would indicate the need for a new battery, correct? I believe the battery should be pushing over 10V cranking with most cars, though not sure if the 928 has any different voltage needs. Thoughts?

Alan

I don't think is a real problem. Normally would be above 9V with a new battery - but likely still has life left as long as it turns over sufficiently fast... I don't think its related to any change in behavior

Reconnecting the battery probably does result in the instrument cluster illuminating during its reboot so that part is likely true.

Alan

jwbeck17

Thanks, Alan. I'm trying my best to diagnose this startup issue without spending a bunch more into it as having an injector harness built from scratch ain't cheap, as you could suspect (Kroon Harnesses created it). I did install the harness and there was a point where the car could start with it (though it ran very poorly). Since it got cold and/or wet here in PA, it's not starting. Apart from double checking and cleaning connections and grounds, I am trying to take note of every clue I can to investigate, starting first with electrics. I have noticed that the starter sounds much slower and weaker than in previous starts and sounds worse as it is used. Hence I was thinking either battery or starter being an issue. Would love to rule one out if possible.

Not sure if you can hear my starter in the video, but it sounds sluggish to me. Maybe I should rule out the battery in this case?

I recognize this may not solve my issue with getting the car running, but it may have to be overcome first.

jwbeck17

So I found a video I made years ago with the startup sound as well as the one I just took, keeping my phone outside the car. The video with the mic by the exhaust is from 2015 I think. The one I just took has the phone looking underneath the cabin. The starter sounds much different and has an odd clicking noise, which may be the solenoid.

Still thinking the starter may be done for vs. the battery, but welcome your thoughts.

87m491

Try it with jumper cables and let us know if it changes.

Mrmerlin

Please read the warnings in the WSM regarding voltage assisting starting on a 928

Not sure what this means^^ but if the battery is in question either charge it up or replace it .
If the Starter is in question remove it and have it tested

NOTE adding jumper cables and an extra charging assist to start the 928 can damage,
the relays on the CE panel, the alternator diode pack and or the V Regulator,
the LH computer and EZK.among other things.

Jason you might need to swap in a new set of spark plugs

Dads928

Just my 2c. I've worked my way through the electrical system of my girl for the past 10 years. Fixed, cleaned , diagnosed just about everything. Pulled the cluster half a dozen times sorting out some unusual gremlins, got my cluster solved and my electrical system is 100% now. After all this time, the one thing that did the most to solve problems was dead simple.
There are a couple of weak points when these cars get old. Check the main power cable at the multi pin connector on the passenger fender. Everything runs through that baby. On mine, the main lead where it enters the connector was looking tired. Hard insulation for about 1/2 inch. Closer examination and the stranded wire inside was corroded, green and stiff. Cleaned, deoxit and reattach. Instant improvement. But, by fluke, I was under the car and noticed one of the wires on the starter solenoid looked the same. Took it off and it was terrible inside. Stripped it back, new eyelet, reattach and bingo. My running voltage and idle voltage both improved along with some minor engine improvement as well. I have a digital voltmeter and now I'm at 13.4 even at idle. With everything on max power consumption, I'm getting almost 13 at idle. Increased resistance in the old connections and wires cause all kinds of hard to find problems.
Ive had those connections apart over the years for other work but I guess I just wasn't paying attention.

And yes, the digital dash will light up when reconnecting the battery. Every time, does a reset and you get the production code and software info briefly on the display. Otherwise, dash doesn't get energized until you turn the key to position 1.