dlagerstrom

I recently rebuilt the interior of my '82 US car. Everything is back and working but my central warning is always on. The button on the center console does not reset the light. No other warning lights. I wondered if LED bulbs might have done it so I replaced all LED bulbs with original incandescent. No change.

I am out of ideas. What could be messed up with wiring to cause the warning to be on?

Thanks for any ideas.

-Dave

jpitman2

Disconnect the battery for 5-10 secs, reconnect and tell us when the warning comes on. Do any other warning lights come on with it? It normally comes on at switch on until you press the brake pedal.
jp 83 Euro S AT 56k

dlagerstrom

Warning comes on as soon as I turn the key, even after battery disconnect. No other warning lights. I Normally have my foot on the brake when I start but if not, the brake light warning does come on until I hit the brake.

John Speake

Check out the handbrake adjustment and switch...

dlagerstrom

Interesting. The dash light for the handbrake functions as normal. Are you saying there can be an adjustment problem?

MainePorsche

At the arm for the brake there's an electrical contact.

John Speake

I know that when the handbrake switch is on then the red cancel button will not cancel it.

When I bought my 928, I drove away and 1/2 mile down the road saw the !! display. I tried everything to cancel it until I realised the handbrake was slightly on.

dlagerstrom

Great! Thanks. I will check it.

curtisr

From http://www.porsche928forums.com/view...php?f=5&t=1028 comes this suggestion:

I guess a good way to start tracing the issue is to see if all the warning lights come on with KEY ON. Any that don't could have an issue in their respective system that's causing the Main Warning light to come on.

What I'm wondering is whether the ! is 'gently lit' or 'glowing brightly'. On my CAN '82 it was the former and after pulling the POD and replacing the burnt-out light bulbs it was no longer illuminated.

dlagerstrom

Checked the handbrake switch. Removed and cleaned it. Works great. Made no difference.

When I turn on the key, all lights turn on except the oil level warning. That one is not supposed to go on unless the level is low.

Light is glowing brightly both on pod and center console.

Thanks

curtisr

If it's glowing brightly it's probably trying to tell you that it's time to change something such as the O2 sensor, timing belt, etc. Anyways, here-in may lie the answer...

Source: http://forums.pelicanparts.com/porsc...-question.html

Probably more information than you'd ever want, but here you go:
(From the Porsche Electrical Trouble shhoting and Repair manual)
Operational test
I. Up to Model 83, the warning lamps are extinguished by the engine cranking pulse (terminal 50).
Accordingly, it is necessary to crank the engine, without letting it run, in order to switch off the
warning lamps.
To do this, pull the HT lead, terminal 4, off the distributor and apply it to ground (earth) (screw
heads on crossbar mounting).
I I. From Model 84, the warning lamps are no longer extinguished by the cranking pulse, but by the
voltage rise of the alternator, terminal D +/61.
The switching threshold is in the region of > 6 V, i.e. when the engine starts and if the alternator
charging circuit is in order (voltage rise >6V), the warning lamps are extinguished. This means that,
even when there is a break at D t/61, the warning lamps go off immediately the ignition is switched
on because terminal 15 (+) is applied to the central indicator via the charge indicator lamp.
In order to switch off the warning lamps to test them, it is necessary to separate the multipoint
engine connector in the engine compartment after switching on the ignition (lamp test ). Connect
terminal 1 on connector (front wiring harness) to B+. The warning system,with the exception of oil
level and oil pressure, can now be tested.
ZW - central warning lamp
ZW - central warning lamp
WL - warning lamp / warning lettering
Q- acknowledge button (in center console) - functions together with ZW from Mod. 79.
1. Brake light
Operate foot brake.
- Brake light WL must go off
2. Handbrake
Apply handbrake (or connect cable on handbrake contact to ground)
- Handbrake WL, ZW and Q must light up. The two lamps go off only when the handbrake is
released.
3. Coolant temperature
Pull cable con11ec1or terminal W (smaller connector lug) off the temperature transmitter on the
elqine and colmect it to ground.
- Coolant temperature WL, ZW and Q must light up. Press acknowledge button, ZW and 0 go
off, WL must continue to glow. The WL goes off when the ground connection is removed.
4. Oil level up to Model 83
The transmitter IS fitted on the front of the oil sump. Pull cable off transmitter and hold it
against ground, or additionally connect multipoint connector part of front wiring harness
terminal 6 to ground and attach the connector.
- Oil level WL, ZW and Cl must flash. Press acknowledge button, all lamps must continue
flashing. All lamps must go off when the cable is attached to the transmitter, or when the ground
connection is removed.
4a. Oil level from Model 84
Connect connector P3 (M23 model 85 and later) on CEB to ground (connector remains plugged in).
- Oil level WL, ZW and Cl must flash. Press acknowledge button, all lamps must continue
flashing. All lamps must go off when the cable is attached to the transmitter, or when the ground
connection is removed.
33
CENTRAL WARNING
5. Oil pressure up to Model 83
Separate multipoint engine connector. Use auxiliary cable to apply connector part of front
wiring harness, connector socket No. 2, to ground.
- Oil pressure WL, ZW and Q must flash after about 2 seconds. Press acknowledge button, all
lamps must continue flashing. The lamps must go off when the auxiliary cable is removed.
5a. Oil Pressure from Model 84
Connect connector P2 (M22 model ‘85 and later) on CEBto ground (connector remains plugged
in).
- Oil pressure WL, ZW, and 0 must flash after about 2 seconds. Press acknowledge button. all
lamps must continue flashing. The lamps must go off when the auxiliary cable is removed.
6. Brake lining wear
Separate one plug connection of a lining contact segment. (Front left-hand side of engine
compartment at level of brake master cylinder.)
- Brake lining WL, ZW and Q must light up. Press acknowledge button - ZW and 0 go off,
WL continues to glow. Reconnect plug connection, WL continues to glow.
Note: Allow the individual warning lamps (WL) to continue glowing in the following tests until
you have checked through all items - otherwise you will have to keep repeating the
procedure as per Section I or il.
7. Coolant level
The transmitter (float) is located Inside the coolant expansion tank Pull off cable and joln the
cable’s plug connections together.
- Coolant level WL, ZW and Q must light up after about 20 seconds. Press acknowledge button,
ZW and Q go off and WL must continue glowing. The WL continues to glow after the cable
bridge is disconnected.
7a. Coolant level from Model 84
Trip warning as described under 7. Press acknowledge button so that only the WL glows. Fit
hand pump VW 1274 on coolant filler neck and pressurize cooling system to at least 0.5 bar
gauge. Switch off ignition, wait about 10 seconds and then switch It on agaln. The “coolant
level” warning lamp must light up. Depressurize cooling system. Switch ignition off and on
agaln. No warning lamp should light up.
8. Windshield/headlight washer water level
Remove cover plate from CEB in passenger foot well. Connect auxiliary cable to ground and other
end to:
Connector K, terminal 5 (Ml4 model ‘85 and later)
or
Connector Q, terminal 6 (none on ‘85).
(This circuit saves you from having to remove the guard plate in the right-hand wing - in front of
the water reservoir.)
~ Washer water WL, ZW and 0 must light up after about 20 seconds. Press acknowledge button.
ZW and Q go off, WL must continue glowing. The WL continues to glow after the connectlon is
removed.
9. Fuel level
Remove cover plate from CEB in passenger footwell. Connect auxiliary cable to ground and other
end to R15.
- Tank reserve WL, ZW and Q must light up after about 20 seconds. Press acknowledge button,
ZW and Q go off, WL must continue glowing Plug in connector, the WL continues to glow.
34
CENTRAL WARNING
,’I -
::
IL 1
10. Brake circuit failure (up to Mod. 83) deleted from Model 84
Pull off one connector base from the brake light switch on the master cylinder and use auxiliary
cable to join together the opposing connector sockets.
- Brake circuit WL, ZW and Q must flash. Press acknowledge button, all lamps must continue
flashing. Disconnect connector bridge and reconnect connector base to brake light switch -
all lamps, ZW, Q and WL, must continue flashing.
Note: The flashing warning indicator can only be cancelled by briefly disconnecting one
battery cable.
- Repeat Section I or II for the following tests
11. Brake fluid level
A pressure switch (extended float) can be seen at the top of the brake fluld reservoir Press this
switch down - or bridge the cable connection.
- Brake fluid WL, ZW and Q must flash after about 20 seconds. Press acknowledge button, all
lamps continue flashing. Release float pin, or disconnect bridge, all lamps (ZW, Q and WL)
conttnue flashing
12. Tail light/brake light
The tall and brake hght IS momtored by a lamp test unit behind the ZEL Tthe lamp test unit IS
new from Model 84 and can be retrofltted.
Switch on parklng Ilght, depress foot brake (brake light WL must go off). Check rear hght
function on vehicle. In order to check this Item It IS necessary to unscrew the rear light lens at
one side of the vehtcle. - Take out tail light bulb.
- Switch on parklng Ilght.
- Tail light WL, ZW and Q must light up after about 5 seconds Press acknowledge button -
ZW and Q go off, WL must continue glowing.
The tall light WL goes off when the bulb IS refltted. Switch off Ilyht! Remove brake light bulb -
depress foot brake. Brake light WL, ZW and Q light up - press acknowledge button ZW and Q
go off, WL must continue glowing. The WL continues glowing when the bulb IS refitted and only
goes off after the brake has been depressed once.
Note: Ensure that both rear lights (brake/tail light) are fitted with bulbs of the same make
and rating - the central warning will otherwise switch on the warning lamps although
the lights are functioning properly.
12. ABS anti-skid (anti-lock) system
Remove relay XVII from CEB, switch on ignition.
- ABS WL, ZW and Q must light up. Press acknowledge button, ZW and Q must go off, WL must
continue glowing. Refit relay.
13. Tooth belt tension
Disconnect plug connecter in front of belt housing.
- Tooth belt WL, ZW and Q must ligth up about N 3 min. Press acknowledge button -

dlagerstrom

Wow. That is quite a list. Some of those things I have tried but I see some that I need to check.

Thank you for that.

I have unplugged the O2 sensor counter that was next to the passenger seat. I plugged it back in to see if it made a difference but no joy. I don't see the O2 sensor on this test list, does anybody know how to check if that is the problem?

Cadillac art

Dave,

You didn't say if you have driven the car this way. If not, does it go out when you step on the brake pedal?

dlagerstrom

I am driving it. Trying to get to the 200 mile number so the suspension settles and I can do a final alignment. Drives great, everything works but central warning light is always on. Frustrating.

dlagerstrom

I should mention that I have done a huge amount of work to the car over the past 5 years. Made a new engine harness and hard wired the instrument pod to replace the failing flex circuit.

Note that the buzzer is not on unless you open a door or something like that.