sprfrkr

1984 US 928S

I am working on an intermittent no start issue and am going through the troubleshooting outlined in a thread a few below this one.

I have created my jumper wire from posts 86-87 (left and top slots) on relay XIV. Turn they key, no crank. I then tested the jump wire from 87-30 and got starter crank when inserted.

What does this indicate? I had thought I was chasing a neutral safety switch issue (relay already replaced before jumping the relay), but the above my hint that is not the case.

TIA!

Mrmerlin

do you have the correct relay diagram for the CE panel of your year?
it is quite possible to install a relay into the wrong slot and then forget that this was done,
then the car will not ever start

dr bob

Guessing you are in the correct relay slot, since you were able to get it to crank with 30->87 jumper.

Plug a NEW (or borrowed horn) relay into the starter relay socket and try again to crank the starter.

If no start with relay replaced, grab your meter, and test for battery voltage at 86 in the starter relay socket with the ignition switch in "start" position. If none, remove and re-seat connector A bottom left on the CE panel, and retest. If still none, replace ignition switch.

----

For those who didn't know already, the 1984 wiring diagrams in the WSM are next to worthless. Interpolate info from previous and following years.

sprfrkr

Thank you to both the masters above.
The no start condition is intermittent, so all looks normal 90% of the time. Other times I either get nothing, a starter click, or half a starter turn. The rest if the time it fires up instantly.

Moving shift level to ither locations in P and in N zones does not resolve the issue. Will start after 5-10 tries of full key off, turn back on.

Confrats on the sale Stan.

Mrmerlin

Thanks...
based on the info you have a bad relay,
if you dont have new relays to replace the old ones ,
then open up the old relays your using and clean the contacts then put deoxit 100 on the contacts.

Also make sure to verify that the wire connectors on each relay pin are infact seated,
putting in a relay can push the wire connector out the back of the connector housing.


Lastly remove the bottom wood on the CE panel then with a good flashlight,
check the plugged in connectors to see if one of the wires could have pushed out of the connector housing .

NOTE the early cars have this issue, you want to make sure that all of the wires appear to be installed to the same depth, what happens is when the connectors are installed if they are not put on perpendicular to the pins the pins can dislodge the individual wire from the housing a loose wire can cause these intermittent issues

sprfrkr

Thanks Stan. I do have two brand new relays form 928intl I used to no avail. Also, would me jumping the 86-87 bypass the relay entirely?

I will check the connectors though. Thanks.

Mrmerlin

Its important to check the correct locations of the relays and the fuses,
make sure the empty slots are empty in both the fuses and the relays and look for that unseated wire it can sometimes only be one thats loose

dr bob

^^^^ What Stan said.

There are a few fairly reliable resources for relay and fuse diagrams online, including suppliers' websites for 928 Specialists and 928 International. Electron-wrangler Alan here on RL has been sharing some great fuse and relay diagrams. Separately, there are PDF's suitable for use in printing stick-on labels for your CE panel. The best source is likely the original fuse-and-relay card set that came in the door to the CE panel.

Diagnostics start with "relay-relay-relay", fuses if you were fiddle-farting with something and some smoke leaked out, and ground connections after those.

sprfrkr

Thanks again.

I've checked and rechecked the relays and board, now I am on to grounds.

May I ask where the ground for the neutral safety switch is located? I found a ground under the tool box for the battery, but did not find one at the forward wall behind the plastic panel in the spare tire compartment. Does my US84 have one there? I've heard of one below the passenger rear hatch speaker, but do nit see it on the ground diagram.

Mrmerlin

its behind the rear edge of the quarter panel liner remove the RR hatch tie down then the 2 screws that hole the rear edge of the panel gently pry forward look for the brown wire bundle

firemn131

I had a similar no start after I put the engine back in..

Ended up being the shift cable was not secured in the hold downs on the belly. If they are not secure there will not be enough rigidity and the cable will not shift accordingly and cut out the NSW.

sprfrkr

Thanks. The NSW is my likely culprit, but I am surprised the jumped relay terminals to bypass the NSW functionality did not work.

dr bob

Based on your first test with the jumper, the neutral safety switch loop is NOT your problem. The jumper removed all doubt, completely bypassing the neutral safety switch, putting ignition starter 50 circuit directly to the starter solenoid 50.

When you jumpered 30 -> 87 and the stretr cranked, you eliminated possible problems with the 14-pin, wiring from CE to 14-pin, wiring through the front of engine harness to the solenoid, and the starter solenoid and starter motor.

With just those two tests you did with the jumper, your is isolated to the ignition switch itself, and/or the wiring from the switch to the CE panel. Start by removing and replacing the wire connector on the ignition switch a couple times to make sute the pins are clean and the connector is fully seated. Use some DeOxit on the connector terminals if you have some. If that doesn't solve the problem, we can test for ignition switch 50 voltage at the CE panel entrance. The '84 wiring diagrams are fuzzy on CE panel connections, so we'll look at te '83 and '85 diagrams, knowing the wirre colors are consistent through all of those.

docmirror

Far be it for me to step in here, but the other common element in all these scenarios is the starter solenoid. The large yellow wire on the 14 pin at the right fender goes directly to the starter solenoid which throws the bendix forward, and engages the heavy gauge wire to the starter coil. An intermittent in the solenoid winding, or corrosion on the contactors inside the solenoid could cause this fault.

Is the failure related to any thermal changes? Is it more common when hot, or cold? If the relays don't solve this, I would take the starter off, and swap it with a known good working starter for a while. Intermittent faults are a real hassle.

dr bob

Doc--

His first test (first post above) with starter relay socket 30 -> 87 jumpered causes the starter to crank. I think this rules out the starter and solenoid. We have it narrowed down to the starter switch or its connection to the CE panel and the starter relay socket, based in the testing he's done.

This thread is a dovetail of another couple similar troubleshooting threads going on right now.