Central Warning Light comes on when accelerating

[Brett928S2]

Originally Posted by Mrmerlin

FYI 1982 does not have ABS

Hi

Thats interesting as they DO have ABS in the UK in 82....

All the best Brett

[Mrmerlin]

Brett thanks for the additional info, are you sure about the ABS on an 82???

US didnt get ABS till, middle of 85.
IIRC it may have been an extra cost option as early as late 84 or early 85 for the US cars, but not 100% sure.
My early 86 5 speed US car has ABS.
my 84 Euro 928S with twin dizzys did not have ABS and it was an early 84.

My 86.5 auto had an ABS fault when I got it,
the CE panel relay was bad.
The ABS light came on when the key was turned on, fitting a new relay fixed this

[Brett928S2]

Originally Posted by Mrmerlin

Brett thanks for the additional info, are you sure about the ABS on an 82???

US didnt get ABS till, middle of 85.
IIRC it may have been an extra cost option as early as late 84 or early 85 for the US cars, but not 100% sure.
My early 86 5 speed US car has ABS.
my 84 Euro 928S with twin dizzys did not have ABS and it was an early 84.

My 86.5 auto had an ABS fault when I got it,
the CE panel relay was bad.
The ABS light came on when the key was turned on, fitting a new relay fixed this

Hi

My brother has an 84 S and he has ABS (in the UK) although it could have been special order...

I have had BOTH types of ABS faults at different times....

TYPE 1 .... ABS light came on with ignition and wouldn't go out ...was relay...

TYPE 2 ....ABS light came on after moving around 50 yards.... was sensor wire...





All the best Brett

[Landseer]

Introduced in 84. (might have been std in Europe?)

USA option in 84 and 85.
USA standard in early 86.

Right around VIN XXX1000, ie, 86.5, system changed to axles with less tooth count and different electronics.


The 84 Euro we have here has antilock but triggers a warning. Am hoping Brett's experience with relay will help me.

If Stan's 84 Euro was sans antilock, that perhaps indicates it was ROW optional in 84.

[riber.bentsen]

The relay fixed my ABS light as well, but Brett, the 928 was the first Porsche to be offered with ABS and it was in '84..

[mproseusa]

I added coolant to the reservoir and bled the cooling system as instructed in the owners manual (did not need to add coolant after). Took the beast out and made a few "gentle" acceleration runs. Those runs did not cause the Central Warning light to come on. However a couple of WOT runs did turn the light on, AND the coolant temperature Light (at the top of the temp field) did come on. But only briefly. The engine coolant temperature was in the normal range. The COOLANT light at the bottom of the Coolant/Fuel Gage did not come on. That could be due to a burnt bulb, but I'm only guessing. I think I have a coolant system problem, but not sure what it is. Any ideas?

How does one "see" the windshield washer fluid level? All I can see is the filler neck, and through the fender well back to ???

Best regards,
Mike

[Brett928S2]

Originally Posted by mproseusa

I added coolant to the reservoir and bled the cooling system as instructed in the owners manual (did not need to add coolant after). Took the beast out and made a few "gentle" acceleration runs. Those runs did not cause the Central Warning light to come on. However a couple of WOT runs did turn the light on, AND the coolant temperature Light (at the top of the temp field) did come on. But only briefly. The engine coolant temperature was in the normal range. The COOLANT light at the bottom of the Coolant/Fuel Gage did not come on. That could be due to a burnt bulb, but I'm only guessing. I think I have a coolant system problem, but not sure what it is. Any ideas?

How does one "see" the windshield washer fluid level? All I can see is the filler neck, and through the fender well back to ???

Best regards,
Mike

Hi

On the washer fluid level....you CANNOT see it ever.... the bottle is under the inner wing behind the wheel shield and cannot be seen....and its HUGE , it contains around 2 gallons when full,,,, what you do is keep adding washer fluid and water to the filler neck .. until it overflows...
Then you know its full lol...

Hope this helps ..

All the best Brett

[Mrmerlin]

for the coolant i would first replace the heater control valve and the short hose this is a common failure point also replace the cap,
and inspect the bottle for cracks.

top off the fluid in the washer if you dont know if it will hold try filling with water first see if it holds .

As an aside to the washer tank try this,
remove the tank and remove the metal collars in the fill tube and the tank inlet then wash out the tank this will remove all of the rusty crud in the bottom of the tank so it wont plug your washer jets

[Valentine911]

I had my '83 checked at two shops - my alternator was going out and was the cause of the Central Warning Light flashing each time I accelerated from a stop. I replaced it with a Delco model today; seems fine now and gauge shows battery is getting charged (had been at zero)...

[mproseusa]

Thanks for the input, I'll keep plugging and let you know the results.
Mike

[mproseusa]

I continue to drive the beast, and push the cancel button on the Warning light when ever I accelerate! I filled the coolant tank to the very top thinking the sensor was located high in the tank. When I accelerate, the light at the top of the arc of the coolant temperature gage comes on and then the ! light comes on. When I stop accelerating or just reduce the acceleration the light turns off. The coolant temperature is showing normal or even a tad below normal temp. The coolant warning light at the bottom of the gage does not come on. Again, the engine runs great, but there must be something it's trying to tell me. Any more suggestions?
Mike

[Mrmerlin]

I would check the wires at the sender for the gauge, its quite possible that one of the connections is corroded or loose.
the gauge sender has 2 male pins sticking up . refresh the heat shrink on the female connectors

[mproseusa]

Thanks Merlin, I'll work on it today.
Mike

[dcarter]

Sorry to revive this old thread, but I recently purchased this beautiful 82 from Mike, and this issue he was troubleshooting back in 2010 still exists. Since lots of experts were involved in this thread, I thought I'd ask again for any ideas.

To recap the issue, when accelerating briskly, and sometime when taking a turn quickly, the high temp warning light comes on and also triggers the central warning light. The needle on the temp gauge is in the normal zone. The High temp warning light goes off fairly quickly, and when you push the ! button, the central warning light goes off. I've also noticed that at highway speeds, the high temp light sometimes flickers a bit, which triggers the ! light, making me think maybe high speed air flowing through the front of the engine compartment is moving some wires around that may be shorting.

There is lots of talk in this thread about coolant level, but I don't see how that could trigger the high temp light.

I've checked the wiring and plugs to the temp sensor on the water bridge, but they look ok. I also had my son watch the light in the car while I wiggled wires all over the engine compartment trying to get the light to come on, but no luck.

I'm thinking swapping out the sensor might be a good next step. Haven't done a good ground cleaning yet, but need to. To confirm, the high temp warning light gets it's signal from the sensor near the water bridge correct? Is it direct, or is there some circuitry interpreting the signal that could be faulty? If it's the same sensor as on one of my other 928's, I'll just swap it out and test (86.5, 87 & 89).

[Mrmerlin]

swapping out the sensor is a good idea, they do go bad,

Note that there are 2 different sized connectors on the wires,
it is a good idea to swap in new connectors,solder them on.
radio shack has the both sizes of the female connectors.

NOTE also inspect the 14 pin connector and the engine side harness wires for shedding insulation the harness could be shorting .
spray deoxit onto all of the connections

[dcarter]

Stan,

Thanks, I'll check the 14 pin and sensor connections. Have some deoxit as well. I can't quite figure out how acceleration triggers the issue though. The engine does rock when reved, so maybe there's enough engine movement during acceleration to move some bad wiring around, causing a short.

It was good to finally meet you at 3rd coast. I hope you will become a regular...

[Mrmerlin]

It was good to meet up at 3rd Coast.
Great people in the middle of the country.
its probably the 14 pin harness area that is causing the shorting look for shedding insulation,
NOTE this is a common fail point.

[stepson]

Don,
A tidbit that might assist you that I pulled from the WSM (90-29):

The Central warning system monitors the following functions:
1- Oil Pressure
2- Oil Level
3- Brake Circuit failure
4- Brake fluid level
5- Parking brake
6- Coolant Level
7- Coolant Temperature
8- Fuel Reserve
9- Washer Fluid level
10- Brake pad wear
11- Stop lights
12- Tail lights

Either a short/grounded wire or one of these systems is causing the warning.
BTW, the Single Component Test starts on 90-34 of the WSM. It is really very interesting.

[dcarter]

John,

Every time the central warning light comes on, the high temp light comes on first, so I'm convinced it's only being triggered by the high temp warning light circuit, but the needle shows normal temps. I'll check out the test procedures.

[stepson]

Don,
I saw in the earlier posts what was happening. I am pretty sure that Stan got it right in the last part of post #35. Since the temp sensor wiring runs through the front engine harness, I would guess that somewhere in that circuit, a lack of insulation is causing the false (I presume) reading.