- #651 of 1085
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Re: Gremlins in a '99 Suburban [burdawg]
by goose249
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Jun 14, 2006 (3:57 pm)
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Replying to: burdawg (Jun 14, 2006 6:10 am)
I'll give that a try. I was also wondering if it could be an ECM. It used to be that I could wiggle/replace the ECM1 fuse under the hood and the problem would correct. Lately that hasn't fixed the problem
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- #652 of 1085
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Re: Gremlins in a '99 Suburban [goose249]
by 99tahoe44
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Jun 17, 2006 (7:50 pm)
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Replying to: goose249 (Jun 13, 2006 6:58 pm)
Hi! I have a '99 Tahoe with the same symptoms. I already spent two full days trying to find the problem. No success. And I have the GM factory book + Snap On MT 2500 Diagnostic scanner. The only thing that I found that in the event of the ABS light coming on the 4wd light coming on and the A/C shut off it seems that these systems seem not to get any power. It this event I can't even get to the ABS and 4WD systems with the diagnostic scanner. The scanner simply says it is not connected. Once the ABS and the 4WD light is off the diagnostic scanner succesfully connects but there are not error codes stored. I started suspecting a faulty ingition switch as well (just as burdawg suggested). But I have not changed the ignition switch yet as it seems to be quite some hassale. So I'm still investigating in some other direction. Should you change the ignition switch and should it solve the problem would you please let me know. Of course if I find the problem first I will share any of my findings with you as well.
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- #653 of 1085
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Electric Cooling Fans Running Long After Shutdown
by jswan3
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Jun 17, 2006 (8:07 pm)
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I just got a new 2006 Honda Accord and I have found the cooling fan or fans running long after the engine has been turned off. The first time was thursday when the fans came on about an hour and 10 minutes after shutdown and then tonight they came on briefly at 10:30 PM after the car had been parked since 12:45 PM which was almost 10 hours latter. I will be taking it in for service next week but was wondering if anyone can shed any light on this problem?
Thanks
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- #654 of 1085
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Re: Gremlins in a '99 Suburban [99tahoe44]
by burdawg
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Jun 18, 2006 (8:44 am)
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Replying to: 99tahoe44 (Jun 17, 2006 7:50 pm)
Before doing any time consuming and expensive repairs, have you checked to see if these subsystems are getting power when they should? A factory wiring diagram would be essential for this I would think.
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- #655 of 1085
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Re: Electric Cooling Fans Running Long After Shutdown [jswan3]
by burdawg
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Jun 18, 2006 (8:46 am)
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Replying to: jswan3 (Jun 17, 2006 8:07 pm)
That doesn't sound right to me. After cooling for 10 hours they surely shouldn't be on. Sounds like a faulty temperature sensor to me.
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- #656 of 1085
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Re: Gremlins in a '99 Suburban [burdawg]
by 99tahoe44
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Jun 18, 2006 (10:44 am)
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Replying to: burdawg (Jun 18, 2006 8:44 am)
Thanks. I will check with voltmeter today. To reiterate the exact symptoms (which are intermittent): ABS light comes on. At the same time A/C stopps working and the 4WD light comes on. If I pull the fuse #12 (25Amp HTR-A/C fuse) then AT FIRST everything will work except the A/C of course. But later the ABS light keeps coming on. Then usually the ABS light start flashing intermittently, sometimes even kind of pulsating-dark like it keeps trying to come on but does not. If at this moment I try to e.g. flip the the heated seat switch the ABS light becomes steady on. That's why I think there is power problems or ground problems. If instead the heated seat switch I turn on the rear A/C the same thing happens. And of course the same thing happens if I put the fuse back on. Trying to isolate the problem I have connected and disconncted everything (Relay, HVAC Panel, Blower Motor, Resistor... everything) on the front A/C (while the 25Amp A/C-HTR Fuse#12 was in place) but nothing seemed to make a difference. Only it I pull the 12Amp Fuse#12 the ABS light goes off and then some time later again becomes kind of pulsating. In this condition if the ABS light pulsates the 4WD buttons are not lid and the rear A/C (which is independent of fuse#12) stopps working. It is all very strange. As mentioned I have the GM OEM factory repair book. It is a huge 4 band encyclopedia. But unfortunately there is no reference on the ignition switch wiring. I guess for theft deterrent purposed. The most you see on the wiring diagrams is e.g. HOT on RUN. But where RUN gets its power is not explained. Actually the only reference is in one short diagnostic table. It just says if Ignition Switch is not operating properly replace the switch. And on another chapter there is some pictures how to do it. Burdawg you are my only reference that suggests it may be an igition switch problem. I kind of start beliving that this is the problem as well. But again today I will make some voltage tests. If you have any other ideas please share them. ThanX
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- #657 of 1085
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Re: Gremlins in a '99 Suburban [burdawg]
by 99tahoe44
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Jun 18, 2006 (2:59 pm)
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Replying to: burdawg (Jun 18, 2006 8:44 am)
Actually I did find the ignition switch wiring diagram in the factory book. It is in Book 4, Page 8-352 and 8-353. I also checked the voltage in the affected circuits. The affected cirvuits are the switch control circuilts of: RR-AC, HTR-AC, 4WD, Brake and Cruise Contorl. If the problem occurs the Voltage is just below 6V. This circuit gets its power directly from the igigiton switch. 6V is probably not enough for the relais to operate. In the main circuit so on the relais/switched side the Voltage is 12V. There is one catch however. I also discovered that some glorious alarm insalling guy installed an alarm. Guess where. He interrupted the power that comes form the ignition switch and goes to these control circuits. And revired quite a bit. He cut and spliced wires (I hate these useless alarms - unfortunately the previous owner of my car built it in). So the whole problem could come form the alarm too. But the alarm works fine + I did not have the time to investigate in this direction today. This will have to wait for next weekend.
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- #658 of 1085
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Re: Gremlins in a '99 Suburban [99tahoe44]
by burdawg
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Jun 19, 2006 (7:26 am)
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Replying to: 99tahoe44 (Jun 18, 2006 2:59 pm)
Did you mean that the input to the ignition switch for the accessory systems is 12V, and the output is 6V? If so then the switch is a definate suspect, but I would disconnect the aftermarket alarm to make sure it's not loading the circuit down.
If you don't want the alarm then my suggestion would be to remove it and put everything back to original.
6V isn't enough for these circuits to operate on. It's quite possible that this aftermarket alarm is failing and loading the circuit down, or some sort of related problem.
The right way to wire in added systems on modern vehicles is to get power directly of an accessory terminal on the fuse panel or directly from the battery (fused in both of course) and not to tie in to other systems for DC power. Modern vehicles have so many sub-processors running (70+ average today I read) that it's risky to disturb any of them with unknowns.
I always suspect these aftermarket electronic add-on systems since a great many of them are built real cheap.
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- #659 of 1085
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Re: Gremlins in a '99 Suburban [burdawg]
by 99tahoe44
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Jun 19, 2006 (9:41 pm)
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Replying to: burdawg (Jun 19, 2006 7:26 am)
Yes, every time the problem occurs there is approx. 6V in the relais operating circuit side measured at the fuses for the affected circuits. And sometimes the voltage drops to even approx. 4V. So yes, I suspect the ignition switch as well. By the way I called my local chevy dealer here in Torrance,CA and they have the switch on stock. It is $190. I won't have time until next weekend to do anything. But I will be sure at the car Saturday at daybeak testing the switch. By the way Burdawg thank you for following up with me on this issue. Your input was already very inspiring and so it helps a lot. By the way the ignition switch is retained by a screw that looks like a T6 inverted Torx. I have never seen anything like that before. I'm trying to get some socket for it by this weekend just in case.">
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- #660 of 1085
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Re: Gremlins in a '99 Suburban [burdawg]
by 99tahoe44
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Jun 24, 2006 (7:53 pm)
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Replying to: burdawg (Jun 19, 2006 7:26 am)
Hi! So finally today was circuit testing day. Initially with the AC-HTR Fuse 12 pulled the problem did not occur. In all circuits there was a healthy 12V with engine off and ignition in run position. In particular I probed the wires immidiately before and after the ignition swich as well. There was 12V before and after in all circuits. Initially I was even trying to turn the ignition on and off many times trying to produce a problem in the switch but the result remained always a healthy 12V on both sides of the switch. Then when I inserted the AC-HTR Fuse#12 the circuit after the switch immidiately crashed to 6V. The battery side of the switch remained at 12V. So I went to GM and bought an ignition switch. For just under $190. That is where I'm now. I can't built it in because I can't get the other switch out. It is retained with two torx-MALE-HEAD bolt that loolks like a T10 or T15 tip. And you just can't get to both of them with wise-grips. Also there is the upper plastic steering wheel shroud that has to come off too. But that is retained with two torx-MALE-HEAD bolts that is just like a T20 tip. So again nothing is going to happen until next weekend.
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