So i bought a 2000 blazer,
the 4x4 doesnt work, service 4x4 light on, no lights on the selector switch at all, no sounds when i push one...
the gas gauge dont work, low fuel light on
the temp gauge didnt work so previous owner installed an aftermarket gauge
the cruise works but not lights to say its doing anything
the gear selector indicator lights up but no marker for the gear its in
the back hatch wont pop and seems no power getting back there... (changed out the switch)
the rear wiper dont work...
and the battery light on cluster stays on but i have driven it lights on for 139 miles and its not dead so must be charging...
(i have a 1999 parts blazer)
is there anything that links all these issues?
ive checked all fuses
im gonna swap out the cluster to one i know works... but i dont think the cluster is gonna affect the rear wiper or 4x4 or hatch issue...

its so much im not sure where to start
any help would be great
thanks for reading

 

I've never had a problem like this but here is what I'd do as a start. First see if there are any OBD codes. You might find that there is an issue with communication to or with the body control module (BCM). The BCM controls lots of the systems on these trucks.

 

Will see if i can find someone to scan it deeply for me
thanks
i will post what i find out

 

I agree with Christine on starting with OBD codes.

Another thing to do is if any work or service has been done recently, check that any ground connections in those areas is properly connected and clean (not corroded).

 

Along with the suggestions from Christine and El_Beautor, if the PO added wiring for that aftermarket temp gauge, I'd want to remove that gauge completely from whatever circuits he tied it into and put everything back to its original state to start with a clean slate before I started troubleshooting. Same goes if he added an aftermarket thermostat in the block that is not of the design of OE. Don't just unplug it, but completely disconnect any non-original wiring and put all wiring back to its original state (including on OE design thermostat).

If you do not have the service manual/wiring diagrams, you might want to consider a subscription to either Alldata or Mitchell which provides not only the service manual but also OE and non-OE (colored) wiring diagrams before you dive into the troubleshooting.

Outside of the potential BCM/gauge issues, if I am understanding correctly your rear window glass motor does NOT operate from BOTH the dash AND the rear lock cylinder on the back of the truck?

Power for the motor comes from Fuse 7 (MIR/LCK) (Hot At All Times) whichever switch you are using. However, control thru the BCM comes from only the dash switch. The rear lock cylinder switch to open the glass does not involve the BCM and should work regardless of a BCM issue.

If you already have panels removed, take a look at this thread where it shows the plastic channel which includes several circuits to the rear of the truck…including the power for the motor and control wires for the rear cylinder lock.

https://blazerforum.com/forum/lighti...rcuits-105801/

Note Fuse 14 (LCK PWR) feeds the lock/unlock relays in the BBEC (Body Bussed Electrical Center) tucked behind headlamp switch in the dash, so if you haven’t, I would test both sides of Fuse 7 and 14 by measuring voltage with a DVOM to start with. Then start circuit testing from the motor side (once again IF the motor isn’t working when you operate the rear lock cylinder switch).

One last thing, if the PO added an aftermarket stereo (or any other aftermarket stuff) check to see if he butchered into any circuits installing.

 

This thing has had stuff done all over the place...
i checked and i have power at the hatch switch, but that power cuts when i press the button...
no power at the actuator
i swapped the 4wd module in the passenger kick panel with one i know is good from a running diving blazer and it clicked as soon as i plugged it up but still no lights on the switches (which i swapped as well)
still says service 4wd...
i swapped the cluster and no change except now my truck has 100000 more miles on it lol
havent found any buddys yet with a scan tool that can read all the way down into the 4x4 codes...
im gonna pull the t-case motor off that 99 i got and put it on the 2000... i know it works... see if that accomplishes anything...
After that i will drop the tanks and swap out the sending units and see if that helps with the fuel hand... its got some aftermarket lights so ima unhook all that see if it helps that battery light... then swap in the newer alt from the 99 that i know is good...
the shift indicator is weird... when i cut the engine the indicator shows up... shows park when start it... then when i shift its gone again...the letters light up but wont show selector position... but when i cut it off it pops on... ive jiggled the key fumbled
around the wiring... no changes...
so idk
will keep you guys posted what i learn

btw yes on aftermarket stereo, aftermarket lights... the hatch doesn't pop from dash or tailgate... its a 2dr w a tailgate... rear wiper dont wipe but rear washer button makes the pump come on...
ive checked and no power to actuator when pushing either button...
it looks like he tied into 2 wires on the hatch dash button for who knows what... grey and black... black seems to be a ground and grey has power on it but loses power when i push the button...

also i notice that i dont have to put my foot on the brake to shift out of park... idk if that make any difference with the 4x4 not working
and also the motor and transmission have been swapped by PO as well

update
went to back as shown in link and started doing some checking... i jumped across the button hatch button wires in the tail gate and the actuator did its job... one problem down... that rear button is bad!!!!
still nothing on the front button or any of the rest of the 100 issues but its a start !!!

 

New update:
i went and checked the rear hatch button in the rear of the 99 and it worked perfect.... pulled it out and plugged it in the 2000 and gave it a test push... nothing... again i jumped the green to the black terminals and it actuates... checked continuity on the button while pushing it... dead... plugged back in 99... dead... whats happening here?
so i took the button apart and cleaned the contacts good and now the button works and the hatch pops from outside like it should but the inside button still no work

also i find that when i turn the switch on the tccm clicks and the lights on the switches all flash on then off and stay off and nothing else happens... no lights nothing when pushing the buttons...