No start but have power/ Tahoe running and then gages drop

[swathdiver]

If it'll help, post up the codes.

 

[TaboltB2015]

If it'll help, post up the codes.

P0700 TCM says replace ECM
U0155 lost com w gateway/ instrument cluster says Replace BCM
U0170 PPS sensor a
B1395
B1529
B2652 BCM or fuse block
B3600
B3922
All of those B CODES for some reason are air control related

This one caught my attention
U0164 Data line wire// states the problem I’m having
U0140
U0198

U0214 —
U0198
Both are battery cables, battery ignition switch or BCM but the BCM is a new remand

Battery cables are new other than the one that goes to the fuse box


Theses are the codes I had last time after I replaced the BCM

U0645 a/c clutch relay which every time I have this problem the ac stops working

U0073 control module bus off
U0121 lost com with ABS
U2100 can bus
U0100 lost com w ecm/pcm
U0101 lost com w transmission
U0102 lost com w transfer case
U0140 lost com w BCM
U0198 lost com w telematics
B0423 temp control 2
B3779 air flow control 9



Sent from my iPhone using Tapatalk

 

[swathdiver]

Thanks Brandon. Your descriptions of what these codes are for does not match my shop manual. P0700 is a request from the TCM to the ECM to ask it to illuminate the Malfunction Indicator Lamp. All of the "U" codes are a loss of communication with the BCM and many of your "B" codes are due to insufficient voltage.

Ok, I just reread the whole thread, my memory is not so good. Thus far, you've swapped out the battery and determined that this is not a battery problem. This is not a ground wire problem, nor a battery cable problem. You replaced the BCM with a reman BCM. I believe that this is your problem. This one is no good either.

Can your scan tool double check the integrity of your charging system and voltage within the various modules? Either way, I still think it is the BCM.

 

[about20ninj45]

Do you have an after market radio or alarm?

 

[TaboltB2015]

Thanks Brandon. Your descriptions of what these codes are for does not match my shop manual. P0700 is a request from the TCM to the ECM to ask it to illuminate the Malfunction Indicator Lamp. All of the "U" codes are a loss of communication with the BCM and many of your "B" codes are due to insufficient voltage.

Ok, I just reread the whole thread, my memory is not so good. Thus far, you've swapped out the battery and determined that this is not a battery problem. This is not a ground wire problem, nor a battery cable problem. You replaced the BCM with a reman BCM. I believe that this is your problem. This one is no good either.

Can your scan tool double check the integrity of your charging system and voltage within the various modules? Either way, I still think it is the BCM.

I’ll have too lol when I’m on lunch, I started thinking the same when some of the codes on identifix said BCM maybe I just need to spend the little extra to get it from the dealership if I remember my shop price was like 215? I also thought about putting the old on back in and seeing if and what codes I get back, the codes are copied from the scanner with out all the word I just took that part or module that was showing up and wrote it down


Sent from my iPhone using Tapatalk

 

[TaboltB2015]

Do you have an after market radio or alarm?

I don’t everything is factory, I was just under the dash yesterday and for sure nothing aftermarket


Sent from my iPhone using Tapatalk

 

[about20ninj45]

When my gauges did that, it was because there was a short between the databus wires and ground when there wasnt supposed to be one, yours is GMLAN. I dont have the pinout to the gmt 900 vehicles but you should be able to find one and do a reseistance check across them to ensure there are no breaks in the wires or shorts. Measure between the data high wire and the data low wire with the vehicle off. You should measure about 50-70ohms of resistance, if you dont, then you have an issue.

 

[jlee]

Reason I suggested the cable to the fuse box is the history of issues with the mega fuses (new fuse and block comes with the cable) and you saying that you jiggled the fuse block area to get power back.

https://www.amazon.com/gp/aw/d/B0016IXANY?psc=1&ref=yo_pop_mb_pd_title

 

[TaboltB2015]

Reason I suggested the cable to the fuse box is the history of issues with the mega fuses (new fuse and block comes with the cable) and you saying that you jiggled the fuse block area to get power back.

https://www.amazon.com/gp/aw/d/B0016IXANY?psc=1&ref=yo_pop_mb_pd_title

I’ve already replaced the mega amp fuse it came with the wire that goes to the starter


Sent from my iPhone using Tapatalk

 

[TaboltB2015]

When my gauges did that, it was because there was a short between the databus wires and ground when there wasnt supposed to be one, yours is GMLAN. I dont have the pinout to the gmt 900 vehicles but you should be able to find one and do a reseistance check across them to ensure there are no breaks in the wires or shorts. Measure between the data high wire and the data low wire with the vehicle off. You should measure about 50-70ohms of resistance, if you dont, then you have an issue.

Is there a wire diagram that can tell me what wires are which???


Sent from my iPhone using Tapatalk