I have new questions about the E38 wiring. It appears the E38 dual fan wiring is almost identical to the '0411 dual fan wiring. I'm wondering why the diodes are installed. I'm also wonder if anyone has a part number for the dual fan diodes. I'm thinking the diodes are for circuit isolation?
dave w
Dave, after looking at that schematic I can tell you that the diodes are either integral to the fuse block OR the more likely possibility is that they plug into the fuse block like standard blade fuses. I have seen many later model fuse blocks that have diodes in them. I don't have a part # for you, but you can salvage lots of them from various later model GM fuse blocks. I more than likely have a few of them in my toolbox that I'll take a pic of later when I head down to the basement. The purpose of the diodes is to isolate the two fan circuits from each other so that the ecm can turn on fan1 on a low speed with one output and turn on both fans on at full speed with a second. Without getting all crazy with a drawn-out explanation, the diodes are crucial to proper operation with that particular wiring and solenoid configuration.
On a related note, I do have a little bit to add on your other threads pertaining to this same project that you're working on. It will take me a while to type up those posts though, so it will be later in the day before I can reply to those topics.
Hope I was helpful,
Phil
1999 GMC Sierra 1500 standard cab long bed 4.8 V8 2WD - A work in progress.
2000 Grand Prix GT sedan 3800 - My new daily driver inherited from the wife via the insurance company totaling it out after a minor collision.
2006 Grand Prix GT sedan 3800 Supercharged - The wife's new grocery getter.
I was looking through the harness for the Transmission Control Module (TCM) plug, then I learned that the TCM for the 6L80E is inside the transmission ... the internet is usually a good source for information? It might seem odd to some members that I did not know where the 6L80E TCM was.My main role in this conversion is wiring and the computer flash (the fun stuff
).
dave w
Yes sir ... 6L80/90 TCM connector looks like this ...Originally Posted by dave w
Attachment 7012Attachment 7013
Makes it a pain in the ass when replacing a bad transmission. Have to haul truck to dealer to get replacement trans/TCM flashed so it will communicate with ECM.
89 K1500 Scottsdale 5.7L 5spd 3:42 RamJet cam Dart iron TBI heads 427 PCM swap
95 C2500 Cheyenne 6.5L turbo diesel 4L80e 4:10 DB2-4911 Manual pump conversion 0411 PCM trans control 2Bar COS
05 Outback XT 2.5L turbo gas auto
The T43 actually isn't too oppressive to work with. The newer ECMs (E38 / E67 / E78 / E83 / E92) need a GM dealer / TIS flash if replaced - as tuning software cannot read / write the throttle control portion (second core) of the ECM.
The T42 / T43 / T76 TCMs can be completely reflashed using tuning software - making them a little more user friendly.
I've noticed some "brake" related pins in the E38 computer.
The pins I have questions about are on the X1 connector (Black 73 pin connector):
X1 - 26 Brake Apply
X1 - 42 Brake Apply
X1 - 54 Brake Apply
Are the above pins inputs / outputs from ABS? Are the above pins inputs / outputs from somewhere other than the ABS?
The other pin I have a question is:
X1 - 09
I'm thinking this is from the brake switch and in a Normally Closed input to the E38 computer?
Thanks,
dave w
I believe that these are generally not used with E38 non-Hybrid trucks. Hybrid uses pin 54 for fan control. V6 trucks (E37 ECM) does use these pinouts.
Can you post the schematics your question is based on ?
Gen IV brake input logic is the opposite of Gen III.
Gen III PCM receives 12 volts when the brakes are NOT applied - and this circuit is interrupted when the brakes are applied - a Normally Closed circuit.
Gen IV ECM / TCM receive 12 volts when the brakes ARE applied - and this circuit is interrupted when the brakes are released - a Normally Open circuit.
I do not have schematics, I'll need to research (visit my local public library) for the schematics.
dave w
alldatadiy.com or eautorepair.net/
Should have any and all diagrams you need
Agreed!
My local public library has alldata online at the outrageous price of FREE!
The .pdf files I attached earlier in this thread are from the pages I printed at my local public library.
I admit, I have a 14 mile round trip (freeway speeds mostly) to get to / from the library. Not exactly free.
dave w
Ah!. Makes sense!.
If you need anything I have alldata and all of the domestic disks here.
I know it's been a while since I posted about the diodes, but I've not had much time for anything lately. I'm not sure if you found any more info on the diodes either, but here are a couple pics I took of one that I dug out of the toolbox. There are different ones and this one is for an A/C system IIRC, but this will give you an idea what they look like.
IMG_20140424_121213501.jpg IMG_20140424_121411548.jpg IMG_20140424_115401900.jpg
1999 GMC Sierra 1500 standard cab long bed 4.8 V8 2WD - A work in progress.
2000 Grand Prix GT sedan 3800 - My new daily driver inherited from the wife via the insurance company totaling it out after a minor collision.
2006 Grand Prix GT sedan 3800 Supercharged - The wife's new grocery getter.
I have learned there is a Brake Pedal Position Sensor.
X1 - 26 Brake Apply ~ Yellow wire Circuit 5361
X1 - 42 Brake Apply ~ Brown wire Circuit 5360
X1 - 54 Brake Apply ~ White wire Circuit 5359
I will need to disable the both P057C and P057D Brake Pedal Position Low / High.
I was not able to find a schematic for connector X1 - pin 09 brake switch.
dave w
Found some Delphi part number 12135037 diodes at Mouser http://www.mouser.com/ProductDetail/...F%252bQTKos%3d
dave w
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