98 Blazer LS

2014:
Intermittent key off battery draw problem arises.

Summer 2016:
Replace all battery cables, battery, and ignition switch.... Problem seems to be solved.

End of September 2017:
Cluster issues:
Notice PRNDL and odometer LCDs develop an intermittent flicker.

October 6th 2017:
Cluster issues:
When key is cycled to on position, I notice that only the mil, sir, and charging system warning lights are Illuminating. The charging system warning light flickers when harness on top of cluster is jiggled. When harness connector on top of cluster is given pressure towards the backside of the cluster, the charging system warning light and all the other warning lights illuminate properly as they should. When harness connector to Cluster is held in this position and key is cycled back to off and then back to on, the fuel pump Prime sounds like the pump is getting proper voltage, courtesy lamp system is at full brightness and when key goes to crank starter solenoid gets full Voltage...12.6-12.9. Truck starts. When harness to Cluster is left alone and key is cycled to on, as stated earlier, the mil, and sir warning indicators illuminate fully with a flickering charging system warning indicator, the courtesy lamp system is about half brightness, the fuel pump Prime sounds weak, and when the key is turned to crank the starter turns about once before it kicks out and the solenoid repeatedly begins clicking. Also get clicking sound from ignition switch module area underneath Dash. Call wire to solenoid on meter in this situation shows 10.9- 11.4 volts.

October 9th 2017:
Remove cluster.
Do some reading, find some data about silver migration on GM clusters from 97 to 2003 model years due to use of non leaded solder on cluster boards.
Clear solder from harness pins on back of board and re- solder with 40-60 rosin core.
Problem appears to be solved. All Cluster warning indicators illuminate properly through the key cycle and crank and release back to on. When truck is running all electrical circuits operate nominally.

2 Days Later:
Cluster problem comes back.
All previous symptoms are still present. Get mad at cluster and break the Wire harness connector and part of the circuit board off of the cluster. Order remanned cluster. Will hopefully be here by Friday.

Note:
Truck does have aftermarket radio ... But after ignition switch replacement Etc, in summer 2016, unit operated properly, illuminated properly, held memory settings, Etc. No battery draw issues with aftermarket radio installed after the 2016 services performed.

Notes & Questions:

1. Suspecting this cluster issue could have been the problem the whole time, although after reading "the anatomy of an ignition switch", I'm glad I went ahead with that replacement in 2016, although I installed a store brand ignition switch manufactured in Mexico. I'm leaning towards ordering a ACDelco or Delphi (not sure which one produces the OEM switch 4 the 98) switch and installing even if my current ignition switch turns out not to be the problem.

Overkill?

2. I have decided to upgrade to a deep cycle/starting dual purpose AGM battery because of the accessory load I run battery direct.

Does anyone foresee any complications with alternator or fuse relay Center by using such a battery?

3. With the aftermarket radio installed, the conductor for the speed control voluum feature on the factory radios is not connected to anything. (Of course I have a lever nut on the end of it so it doesn't short to ground) I was reading that in the Trailblazers anyway, that there is a module adapter needed if an aftermarket radio is installed for the class 2 serial system to operate properly.

Does the 98 model year use this type of communication between modules?

Do I need to look into purchasing some sort of module adapter between the after-market radio and the bcm, so the BCM is satisfied?

Is leaving the conductor for the scv system unconnected to anything possibly keeping the BCM in awake mode?

4. Aside from unlocking truck with keyless entry or opening a door/tailgate, what else takes the BCM out of sleep mode?

I have tested the door latch switches on the two front doors and they are operating properly. On my truck the physical door pin switches for the two front doors on the side of Dash are still there and there are conductors running to them, I thought they were not used anymore, with the rap system using the door latch switches..... With that being said where do the conductors that are hooked up to the physical pin switches on the side of the dash lead to, the BCM? The pin switch on driver side broke and fell out. Not sure when that happened, but could that be keeping the BCM in awake mode? Does Closing that circuit by connecting the two conductors to each of those physical pin switches indicate door open or door closed? The missing drivers side pin switch conductors are not connected at this time.

3. My glove box lamp socket and switch is completely missing. I assume that with just the two pin harness connector sitting there, that would indicate a door latched situation... But regardless there is no damn bulb even hooked up anyway because there's not even a socket for a bulb, but could that possibly be keeping the BCM in awake mode?

4. If I decide to completely isolate both power sources to my aftermarket radio, and make them battery Direct like all my other accessories, is there anything I need to attach to the factory-installed power supply conductors to satisfy the BCM?

With my DMM connected in series on the negative side of the battery, after shutting all doors and locking truck with key fob, as expected, I get current draw through the TBC 10 amp fuse in the under hood fuse and relay Center. After a bit, the power draw drops down to .0204 with DMM set on 10 amp scale.... Pardon my dumbness, but is that acceptable or is that too much... My brain is so fried I don't know if that is 204 milliamps or 20.4 milliamps or 2.04 milliamps.

My conclusion is that the BCM is powering down to sleep mode properly, but at some point is getting woken up by either the missing glove box switch, the missing drivers door pin switch which is not supposed to be in use anymore but somehow still remained on the design specs, or the un-connected scv conductor from the BCM itself, or maybe...probably.....I mean.... more likely woken up by the faulty cluster or a faulty cluster wiring harness, hence the flickering odometer and PRNDL LCDs, putting a draw back on to my over drained and recharged, and over drained and recharged, and over drained and recharged economy starting battery giving me issues with starting, in combination with the malfunctioning Cluster's contribution during the key turn and starting process, and with all of the key turning and charging and boosting and more key turning and cranking and more cranking and then some more charging and boosting and little bit more key turning and cranking that undoubtedly subjected the dura puke, made in Mexico ignition switch contacts to enough Arc flashing to burn a path all the way to China, where most of the cheap electronic stuff we buy from supposid american-based companies are manufactured, for instance...my aftermarket radio. I'm also recommending to myself to install the premium, more stable, AGM dual purpose battery, and not to bring politics into automotive repair. So if I can follow my own recommendations to myself, this extremely frustrating problem of dependability will not return until the truck itself is no longer mine and is being driven around in Mexico by a teenager who currently works for AutoZone and doesn't get paid enough to buy the newer gm truck he wanted....because GM has the best truck commercials around. I forgot to mention that he would have enough $ for that newer truck if he works on building that wall that his government is going to pay for.

Thanks in advance to anyone who answers any of my questions about the BCM.

Regards,


The guy that can't follow his own recommendations.