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Ask GM Master Tech 01 Your Own Question
GM Master Tech 01
GM Master Tech 01, GM Master Technician
Category: Chevy
Satisfied Customers: 337
Experience:  GM certified master technician 10 years experience
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Replaced the heater core in my 1994 s10 blazer. Now it will

Customer Question

Replaced the heater core in my 1994 s10 blazer. Now it will not start. Disconnected battery before starting. Voltage at battery is arond 13 volts.
Submitted: 8 years ago.
Category: Chevy
Expert:  GM Master Tech 01 replied 8 years ago.

Check for power at the red wires in this schematic at the ignition switch. let me know what you find.


Customer: replied 8 years ago.
Though I have not checked power there, I assume there is nothing there since my turn signals and blower motor do not work in acc or run.
Expert:  GM Master Tech 01 replied 8 years ago.
It looks like you might have popped a fuse. I'll pull the diagram,Did you get everything plugged back in with no pinched wire around the column?
Customer: replied 8 years ago.
I did not get anything pinched putting the column back as I unbolted it again because I thought that's what I might of done. Nor do I think there was a problem when I reinstalled the instrument cluster or blower motor since it's wiring is seperate from the cluster. I did want to let you know that the radio now makes a continuous thumping noise.
Expert:  GM Master Tech 01 replied 8 years ago.

You will need to check for voltag in to the switch at the red wires as this is our starting point.




Customer: replied 8 years ago.
Just wanted to let you know the problem was the battery (go figure). Although it read over 13 volts, when load tested it would drop below 0.16 volts. So I will leave it up to you if you want me to click accept. Just let me know.
Expert:  GM Master Tech 01 replied 8 years ago.
You said you disconnected the battery I assumed it was good as you did. Sorry I over looked the battery. Great job on the repair. You owe me nothing keep us in mind for next time.
Customer: replied 8 years ago.
Would you still be willing to help me with the blazer? Now I'm having weird problems with the instrument cluster. The speedometer and trip odometer do not work. I read in the Mitchell Manual that the cluster needs to be replaced if this problem exist but it did not say if it was just for the electronic cluster or the analog, which I have. I assumed it meant both. It did not suggest any other cause other than static electricity. The check gauges light is on. The oil pressure gauge worked when my daughter took the vehicle this morning but wasn't working when she came home. The fuel, battery and temp gauges work until you turn on the headlights. This also makes the light on the radio go dim. Though I can hear the turn signal flasher, the indicator lights on the dash do not work and neither do the dash illumination lights. I also can not change from low to high beam or vice versa. I assume I might of damaged the switch when I lowered the steering column. I would of never thought changing out a heater core would cause so many other issues.
Expert:  GM Master Tech 01 replied 8 years ago.
The multifunction switch/turn signal switch are known for cuasing wierd things as they will short internally and send power in diffrent directions other than where it should go. Remove the plastic cover around the switch and the steering wheel to remove and inspect the switch.
Customer: replied 8 years ago.
Just wanted to let you know I have not had a chance to look at the multifunction switch. But all the gauges started working. Still no dash lights and the gauges still quit working when I turn on the headlights. I got a different headlight switch from the junkyard but had the same results. My daughter said she should be able to let me have her vehicle tomorrow. If this info changes anything I need to check, please let me know.
Customer: replied 8 years ago.
Here's another one for the lesson books. The problem ended up being the pins on the main harness connector that plugs into the back of the instrument cluster. They were not making complete contact with the printed circuir board. It was just by chance that I decided to spread the pins wider.