Tony

No power there with the key ON or OFF....as seen below. The voltmeter is grounded at the factory point in the wheel well. The reading is shown is Mv.

but..i do get power on the Brown/yellow wire next to it with the key ON. next picture...same ground.

Tony

This pic shows the igntion ON and a good power supply right up to the connector that takes the wiring up into the pod.

Bottom line in this i think is i get power all the way to the POD. The lights illuminate when hooked directly to 9v on the harnes shown below ("to dash"..on the right)

some where between this connection and the bulbs there is an interruption to the 12v supply to the lights.

anyway...digest it, while I get a match!

Tony

some other random shots of what im doing...

and the switch that "Tomshark" was talking about

Kevin in Atlanta

Does it have to be an interruption in the 12 volt? Could be a bad ground.

Tony

I dunno, i have been through this car pretty good and my grounds are good as far as i know. I think i may pull my pod for the sake of not having done it before (probably upgrade the lighting at the time..and fix the "D" light) The ground up under the pod was also used for my extra gauges (boost ..Fuel..water/tranny temp) so i know that is good. The one up under the pax glove box grounds my LM3/LM1..so that is good. As i said, this (lights and reverse lights) havent worked since i owned the car.
Just one of those frustrating gremlins really.

Mrmerlin

do you get any light on the shift indicator if the parking lights are on?? they should be illuminated with in the selector positions

Tony

oooooooooh...good call! Ive had a 5 spd boot on there for ages. Even though this(no lights) has been an issue from day 1 of ownership, i should probably have a look under there to see what i did with the old wiring! dang..never even though of that!... thanks!

Yes...i am the only one that drives my car. "Honey....does the car always cruise on the freeway at 6000 rpm?"

Before ya know it i will be cutting the firewall for a 5spd conversion because i cant get the damn bulbs lit.

I blew a supercharger belt and had the engine and the whole driveline and suspension out last summer!.......that would have been a good time to do it! BUT...i like holding my Frap in hand has i go through 9psi on the on ramp. Good ole Rogbox!

Tony

OK..with time comes progress as i slowly absorb the way these diagrams work and figure out what i should be seeing.
All my bulbs check good except the D light...
The tranny switch works as advertised...
The reverse switch/relay works as advertised.



I spent some time tracing...litterally with colored markers the diagrams tonight and came up with a little test that is easy to do.

My issue now is...i have 12 volts going INTO the tach/PRND32 area (pin 7) but i dont have 12 volts coming out.(pin 8)

Look at the schematic...it may be easier. I lose power somewhere in the pod where the power comes back out. It is the routing/flow of the power that was tripping me up. Power actually goes IN (7)...and OUT(8) on the same harness/connector in the pod. My problem is...it doesnt come out

WHY??

The pod has to come out anyway to replace my burned out "D" light so may be i will fined something then?

Enough to make yer head spin, i tell ya! Damn near pulling an "all nighter" here.

Tony

I'll post this picture again now that i know that the voltage flows both ways across this connector..

Voltage is suppose to flow in the direction of the arrows ive shown. However in my case i dont get the volts across the "orange" arrow..."out from the dash"

underdog928

Good news: After hours and hours of research and pouring over wiring diagrams, I was able to fix my PRND32 lights! And what I found may be a common problem for many of us that have lived without lights for years.

Firstly, let me thank Tony for his great writeup (^^^) and where he left off is where I started.

Tony noted that power comes into the PRND32 light connector on pin 7. This power comes from U25 on the CE panel which is supplied by the ignition switch in position one. Since the PRND32 lights are also powered by the parking light switch, power from there comes into the instrument pod into the back of the Tach, hence the need for a relay on the Tach circuit board to control power to pin 8, which sends 12v back to the switch on the transmission. This power lead (pin 8) puts 12v on both the backup switch and the PRND32 switch so when the contacts are closed by moving the gear selector, that power comes back through the wiring, through the connector in the spare wheel well back to the lights in the Tach.

To make a long story shorter, i found a broken trace on the Tach circuit board. That trace comes from the relay back out to pin 8. That break was why pin 8 never had any power.

So I jumpered that broken trace as shown below:



I left the picture in highres so you can see where I placed the jumper. You can easily tell if you need this jumper by testing for continuity across these two posts. If you don't have continuity, your trace is broken.

Looking at this trace on the other side of the circuit board, it looks really thin where mine broke and could be symptomatic of all 928's and quite possibly it acts like a fuse and opens the circuit.

Hopefully this will help others with this problem.

Tony

Nicely done "Dr Watson'!! Thank you for taking the investigation deeper into the pod and more so sharing it here. I wasnt about to tear that out and create a mountain out of a mole hill. This will be the first thing i check now when i deceide to pursue it again. My guess is youve solved an issue common with MANY owners!
I will follow up here as well when i look at it.

Ive never had the pod out. How hard of a deal is it to get to that image you show. Is there a write up for that?

Landseer

Nice work and pictures. Kudos to all.

Maybe, Tony, you have pictures archived from earlier posts that you can blow-up to diagnose from.

Before I dive deeply into the diagrams, can you recap the functon of that 2 pronged plug/switch under the ignition casting? Is it chime control only?

underdog928

That two prong switch under the pod is closed in ignition position 1 and provides power to U25 on the CE panel which in turn powers the PRND32 and Backup Light circuit controlled by the circuitry on the back of the Tach.

Dwayne's pod removal thread: https://rennlist.com/forums/showthre...ferrerid=33607

Dwayne's Instrument Cluster thread: https://rennlist.com/forums/showthre...ferrerid=33607

Although, you don't need to completely disassemble the cluster to get the Tach out. Just unscrew the 4 sheet metal screws and the 5 brass nuts that hold the Tach in the cluster and it will come out from the front. I did find, at one time, a good writeup on this for replacing the PRND32 lights, but I can't seem to find it now. Maybe someone can help find it for me.

underdog928

Oh, and that switch does power the chime circuit also.

G Man

Does anyone know if the switch on the side of the trans is servicable? My 84' will not start when in "P". If I place the trans in "N" it will start fine. Once in a great while the car will start when in teh P position but this is only after driving the car and things are nice and warm. I'm thinking that the contacts are expanding enough when warm to complete the circuit? Just a guess and I could be way off. What can I say, I'm cheap and would rather fix than replace if possible. I have done the adjustment per the WSM with the same results.