Light that NEVER goes off
02-19-2009, 09:23 AM
#31
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I will have to check it as well, I have a battery drain somewhere within the interior lighting circuit since with the fuse out there is not a drain. Also the interior lights DO NOT COME ON, when the door is opened. They work just don't come on with the door open. I will check the door switches as well the hatch switch as well. I really haven't looked at them at all since I am taking care of A LOT of deferred maintenance under the hood.
11-25-2009, 11:33 AM
#32
As of a week ago, I have the same issue as the original poster to this thread: all cabin lights are on -- with all doors closed.
First, I manually turned-off the interior lights, excluding the passenger kick-panel light and red door jam lights. At least this will decrease the drain on the battery. I have to keep a trickle-charger on it.
I tried disconnecting the various white harnesses near the rear hatch latch, but after waiting a few minutes, the lights remain on, so it appears the rear hatch assembly is not the cause. Is there an easy way to determine the remaining cause - which door switch it could be? I also read the post about it could be the light switch between the front sun visors.
Sorry for any repetition, but I have searched thoroughly on the threads. As some of you know, I'm not much of a "wrench"...
First, I manually turned-off the interior lights, excluding the passenger kick-panel light and red door jam lights. At least this will decrease the drain on the battery. I have to keep a trickle-charger on it.
I tried disconnecting the various white harnesses near the rear hatch latch, but after waiting a few minutes, the lights remain on, so it appears the rear hatch assembly is not the cause. Is there an easy way to determine the remaining cause - which door switch it could be? I also read the post about it could be the light switch between the front sun visors.
Sorry for any repetition, but I have searched thoroughly on the threads. As some of you know, I'm not much of a "wrench"...
11-30-2009, 08:53 PM
#33
I couldn't wait much longer, so I just had the mechanics find the culprit. It wasn't a door or hatch switch. It was the Noise Suppressor Relay that was bad.
Side note: here's a reference/chart that ChuckZ noted - https://rennlist.com/forums/4277984-post11.html with the diagram/location of the XXI relay.
They pulled one from an '89 and it seems to work, but I noticed that when the time-delayed lights shut off, they 'jump' off immediately, instead of the 'faded', smoother off. Isn't this the way it should be or am I smoking something? If so, the '89 apparently didn't have that feature or there's another issue keeping it from that effect.
Side note: here's a reference/chart that ChuckZ noted - https://rennlist.com/forums/4277984-post11.html with the diagram/location of the XXI relay.
They pulled one from an '89 and it seems to work, but I noticed that when the time-delayed lights shut off, they 'jump' off immediately, instead of the 'faded', smoother off. Isn't this the way it should be or am I smoking something?
If so, the '89 apparently didn't have that feature or there's another issue keeping it from that effect.
Last edited by kshipp; 11-30-2009 at 09:49 PM. Reason: added link to other post by Chuck
12-01-2009, 10:19 AM
#34
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.... but I noticed that when the time-delayed lights shut off, they 'jump' off immediately, instead of the 'faded', smoother off. Isn't this the way it should be or am I smoking something? If so, the '89 apparently didn't have that feature or there's another issue keeping it from that effect.
If so, the '89 apparently didn't have that feature or there's another issue keeping it from that effect.Alan
12-01-2009, 11:07 AM
#35
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Thanks for the noise suppressor relay info., Kelly.
I've had a very slow drain in the '91 GT for years. Red door safety lights & glove box lights go off I assume, since they're never warm to the touch. Interior lights seem to be working as they should, so I never was motivated to get in deeper to find the culprit. Using a maintainer helps me to ignore it, but I'd like to find the culprit.
What's a good way to go about testing whether or not this relay is the culprit in my case?
I've had a very slow drain in the '91 GT for years. Red door safety lights & glove box lights go off I assume, since they're never warm to the touch. Interior lights seem to be working as they should, so I never was motivated to get in deeper to find the culprit. Using a maintainer helps me to ignore it, but I'd like to find the culprit.
What's a good way to go about testing whether or not this relay is the culprit in my case?
12-01-2009, 11:31 AM
#36
Race Car
Thanks for the noise suppressor relay info., Kelly.
I've had a very slow drain in the '91 GT for years. Red door safety lights & glove box lights go off I assume, since they're never warm to the touch. Interior lights seem to be working as they should, so I never was motivated to get in deeper to find the culprit. Using a maintainer helps me to ignore it, but I'd like to find the culprit.
What's a good way to go about testing whether or not this relay is the culprit in my case?
I've had a very slow drain in the '91 GT for years. Red door safety lights & glove box lights go off I assume, since they're never warm to the touch. Interior lights seem to be working as they should, so I never was motivated to get in deeper to find the culprit. Using a maintainer helps me to ignore it, but I'd like to find the culprit.
What's a good way to go about testing whether or not this relay is the culprit in my case?
Dan
'91 928GT S/C
475hp/460lb.ft
12-01-2009, 11:42 AM
#37
Rennlist Member
On the MY88 lights circuit, XXi is the time delay relay, is that the one you mean ? That would make sense that if faulty woiuld keep the door lights on.
Xi is a "noise suppressor" for the aircon Just a big zener diode IIRC
Xi is a "noise suppressor" for the aircon Just a big zener diode IIRC
12-01-2009, 11:52 AM
#38
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That is a somwhat unusual failure mechanism. This supressor (looks like a relay can - but only 3 terminals - 1985 & later only) is actually a dual purpose supressor a noise (click) supressor and a spike supressor - two completely seperate functions across 2 unrelated circuits:
Don't run without this supressor - this may well fry your AC head unit relay since one half of the supressor is an inductive spike supressor (zener diode to ground) for the AC compressor clutch circuit. This protects the relay contacts from back EMF when the clucth dissengages.
The other half is a capacitor to ground* connected to the power supply (after the fuse) for the interior lights. When the interior lights first turn on there is a huge initial current spike (about 10 x the steady state current). This (always powered/charged) click supressor capacitor helps to supply some of that initial inrush current and reduce any audible clicking when the interior lights turn on. The series audio power supply supressor inductor on the radio/head unit also help supress coupling this noise.
* it is possible this capacitor can break down & leaks as probably happened here...
A way to test would be to remove the supressor - leave the ignition off - (OR leave the AC switched off - push button switched off, keep the temp control out of the minumim range, recirculate & defrost modes off).
Then see if your current draw drops as normally measured... or run for a while to see if your drain goes away - but be careful with the AC issues...
Alternatively test the capacitor segment of the supressor directly :
Measure the resistance of the capacitor terminals 1 & 5.. this should start out low - but should quickly rise to infinite resistance.
Or charge the capacitor with a battery (say a 9v) then see if adding an ammeter into the circuit you see any continual current draw - there should be no measurable current flowing after the capacitor is charged.
Alan
Don't run without this supressor - this may well fry your AC head unit relay since one half of the supressor is an inductive spike supressor (zener diode to ground) for the AC compressor clutch circuit. This protects the relay contacts from back EMF when the clucth dissengages.
The other half is a capacitor to ground* connected to the power supply (after the fuse) for the interior lights. When the interior lights first turn on there is a huge initial current spike (about 10 x the steady state current). This (always powered/charged) click supressor capacitor helps to supply some of that initial inrush current and reduce any audible clicking when the interior lights turn on. The series audio power supply supressor inductor on the radio/head unit also help supress coupling this noise.
* it is possible this capacitor can break down & leaks as probably happened here...
A way to test would be to remove the supressor - leave the ignition off - (OR leave the AC switched off - push button switched off, keep the temp control out of the minumim range, recirculate & defrost modes off).
Then see if your current draw drops as normally measured... or run for a while to see if your drain goes away - but be careful with the AC issues...
Alternatively test the capacitor segment of the supressor directly :
Measure the resistance of the capacitor terminals 1 & 5.. this should start out low - but should quickly rise to infinite resistance.
Or charge the capacitor with a battery (say a 9v) then see if adding an ammeter into the circuit you see any continual current draw - there should be no measurable current flowing after the capacitor is charged.
Alan
12-01-2009, 03:10 PM
#39
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Sorry to pile on, but here's my weird interior light story ... all work correctly except the one over the rearview mirror. It works the same on both settings (ie. push it from off either forward or backward) ... constant on, never goes off, totally unconnected with the door-controlled lights.
Took it out more than once, all wires are present and attached, no extra, unconnected wires up there. Is the light itself defective to be in constant on when it's set to go on and off with the doors? I could see if one way it didn't work at all when the other way was constant on, just can't think through constant on in both positions.
Took it out more than once, all wires are present and attached, no extra, unconnected wires up there. Is the light itself defective to be in constant on when it's set to go on and off with the doors? I could see if one way it didn't work at all when the other way was constant on, just can't think through constant on in both positions.
12-01-2009, 04:19 PM
#40
Race Car
Sorry to pile on, but here's my weird interior light story ... all work correctly except the one over the rearview mirror. It works the same on both settings (ie. push it from off either forward or backward) ... constant on, never goes off, totally unconnected with the door-controlled lights.
Took it out more than once, all wires are present and attached, no extra, unconnected wires up there. Is the light itself defective to be in constant on when it's set to go on and off with the doors? I could see if one way it didn't work at all when the other way was constant on, just can't think through constant on in both positions.
Took it out more than once, all wires are present and attached, no extra, unconnected wires up there. Is the light itself defective to be in constant on when it's set to go on and off with the doors? I could see if one way it didn't work at all when the other way was constant on, just can't think through constant on in both positions.
Dan
'91 928GT S/C
475hp/460lb.ft
12-01-2009, 04:29 PM
#41
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Try swapping the switched connections - e.g. the two wires that don't go directly to the bulb...
People often take these out and reinstall them with the wires swapped (not well marked).
The solid brown wire should go to the frame connection...
Alan
People often take these out and reinstall them with the wires swapped (not well marked).
The solid brown wire should go to the frame connection...
Alan
12-03-2009, 10:50 PM
#42
Well, the '89 relay is working fine as expected. Out of curiosity, I checked the "big 3" and none carry that relay. I started thinking, geez there are a lot of relays to go bad over time, what will we do?
12-21-2009, 12:53 PM
#43
Rennlist Member
An easy way to test a current drain is to put your multimeter inline with the ground strap, close doors and hatch (lie down in the hatch), wait 1 minute and measure the drain. Then start pulling fuses one at a time and watch for a change. You can do the same with relays. Some things on the 928 are not fused, so it won't work for everything though.
Dan
'91 928GT S/C 475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ftI decided to check this out.
With an multimeter connected between the -battery terminal and the ground strap; on the DCA 20m setting, I got a measurement of 3.73 with the hatch up/interior lights on. After closing the hatch, my measurement dropped to a fluctuation between .14 to .13; then after an hour or so, settled to .05.
Is this an acceptable draw for a 'static' battery?
Last edited by JPTL; 12-21-2009 at 01:41 PM.
