pugtech

On our 1980 US, when I turn on the ignition, only the Brake and OXS lamps illuminate. Once started, the OXS goes out and the Brake goes out when I press the brakes. We purchased it recently and I can't remember if the other bulbs ever worked. Since it's unlikely that the rest of the bulbs are burned out, I'm looking for the best place to start testing. The WSM walks through the testing of each sensor but doesn't really cover the central warning unit or the lamp controller.

The current flow diagram shows the central warning unit but it just has a box around the various bulbs and gauges. So I may not have a separate lamp controller on this model.

The voltmeter works so I must be getting 12V and ground to the common bulb busses.

Any ideas? Thanks!

Alan

The central warning unit is what drives all the warning indicators - check the connections to the pod/in the pod. But first check fuse 12.

On an 80 not sure where the central warning unit is exactly (in the pod? under dead pedal?, console?) who has one and knows?

Alan

SharkSkin

It's not so hard to imagine that all of the bulbs are burned out. Removing the cluster can be intimidating to the uninitiated, but it's really not such a big deal.

The central warning box is under the dead pedal. There are 3 positions the dead pedal can be mounted in, and if you like it where it is then note the current position carefully.

Having said all that, I didn't restore full function to ALL of my warning lights until I pulled the central warning brain and resoldered all of the connections. I found that unlike the cruise brain, the central warning brain has no corrosion preventive coating on the solder side of the PCB. So, that may well be the source of your gremlins.

Of all of the electrical refurb projects on the 928, I think the central warn brain is easiest to do, provided you can solder well. Very easy to get to.

PorKen

'80 is a funky year, IMHO, it's probably the last year of low option cars in the US.

The central warning system was an option, although I reckon most US cars have it. So it's possible it did not come with it, or it was removed. The controller is under the dead pedal until the digital dash (?), whereupon it moves under the console.

Oh, now I see you have the bulb controller, so you probably have the CWS. (Technically you could have the bulb controller by itself.)

Mike Frye

Scott,

There is another option: Some of the bulbs may have burned out, but some may also have been removed at some point by someone who just wanted to sell the car and/or not look at the lights anymore. On the '80MY do you have the (!) light and if so, does it go on with the other warning lights and then off when they clear?

Another option would be to trip some of the monitored functions and see if anything lights up (oil warning, TB tension...) These can be checked by just removing the wires from their respective terminals or plugs, no?

pugtech

I do have the (!) light/switch but it never lights up. I will pull the connectors off the central warning controller and test some bulbs. I'm wondering if there may be a short in the ack switch. Since the Brake and OXS are getting through the controller, I assume it's doing something...

I'll do some digging when I get home. Thanks!

SharkSkin

I wouldn't start pulling wires off the CW box. Start with the [!] bulb and see if it works properly first. You can also pull the connectors off the CW box, and send +12V up the wire to the bulbs in the cluster one at a time to test them.

pugtech

Fixed. The black connector fell off the central warning controller under the dead pedal. I guess the two lights that still worked were fed solely through the yellow connector.

Thanks for all the help!

Mike Frye

Cool! So you've got all of your warning lights back during bulb test as well as the (!) light?

pugtech

Yes. Everthing looks good but I think the PO may have cut a wire on the black connector (Pictured). I'm not sure if it's the Brake Fluid Switch or the unused pin 16. I'm not sure how to orient the connector to the diagram in WSM 90-32.

SharkSkin

That was easy! I just looked at the WSM page that you referenced. I think that the connectors have the pin numbers on them, molded in tiny characters. You may need a strong light and a magnifier to see them. If all else fails, look at the diagram you referenced; pin 13 should get power when the key is turned on, pin 14 should get power only when the key is turned to "start". You should be able to figure it out from there.

Most likely it's the brake fluid switch from what I can see.

pugtech

I reattached the Brake Fluid Level wire and it works fine. I can only imagine that the PO cut it while trying to disable the Low Fuel wire which it actually on the Yellow connector.

Since I reattached the Black connector, the Low Fuel indicator will not go out. I pulled the connector off the sender and the indicator stays on. I confirmed that the sensor wire is not shorted to ground so I think I have a bad Central Warning Brain. I'll have to decide if a low fuel light is worth the cost of a new brain...

SharkSkin

Don't buy a new brain unless you're sure yours is fried. I had some minor intermittent glitches in mine, which hatched into genuine gremlins on the rough drive to Tahoe. I took the brain out, resoldered the connections, and it works perfectly now. Same goes for the cruise brain -- in fact, that's where I got the idea.

Many others besides myself have revived balky cruise brains this way, so I said WTF, give it a whirl. It was actually easier than the cruise brain, because there was no protective coating on the PCBs. If they are all uncoated, it would explain a lot of people's problems with warning lights. I will definitely recommend this in the future to anyone thinking of replacing either part.

pugtech

I would like to extract one of the wires from a connector on the Central Warning brain box to completely rule out the wiring harness. Does anyone know the proper tool and technique?

SharkSkin

Most connectors have a little "latch" tab that engages inside the plastic shell. Generally there will be a gap next to each terminal when you look at the face of the connector that goes against the mating connector. using some sort of thin tool in that gap and pushing that tab back gently will allow you to pull the wire out of the connector. I haven't tried this on the particular connector you're interested in, but I'm guessing a paper clip would do it. Make sure that if you bend the tab down too much, you bend it back before re-assembling. It should give a solid "click" when it it put back in place.

You can see the sort of tab I am talking about on the male connector in this photo: