Ecm & Heater
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From: SPRUCE GROVE ALBERTA
Ecm & Heater
Does anyone know if no codes are set on the ECM, CCM or the heater control head can the non working heater blower be a result of a faulty ecm?
I have gone through the diagnostics charts in the GM manual 3 times now without success... replaced the control head, programmer and blower motor .... the control head will work all of the vaccum heater doors fine but still cannot get the voltage to vary at teh power module of the green / yellow wire from the programmer as the manual says it should. I am going to try the tan serial wires from the programmer/ control head and the programmer to the ecm tomorrow. I am going to try cleaning all of the connections but the tests all say they are connected properly.
Any ideas?
I have gone through the diagnostics charts in the GM manual 3 times now without success... replaced the control head, programmer and blower motor .... the control head will work all of the vaccum heater doors fine but still cannot get the voltage to vary at teh power module of the green / yellow wire from the programmer as the manual says it should. I am going to try the tan serial wires from the programmer/ control head and the programmer to the ecm tomorrow. I am going to try cleaning all of the connections but the tests all say they are connected properly.
Any ideas?
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Originally Posted by golfpro77
any other ideas?
Le Mans Master
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From: San Diego, Ca
Blower Control Module is mounted on the left side of the Evaporator Case, passenger side firewall. Low input voltages from the Control Panel or Programmer (depends on Year) are amplified and directed to the Blower Motor. Make sure the Blower Motor works first by jumping it directly to the battery. Then find the tan wire at the Module which is the input from the Control Panel or Programmer. At 1, voltage should be 2.5. At 10, about 6 volts. Output is purple or whatever is hot at the Blower. Look for 4 volts at 1, 12 volts at 10. If the voltages are correct, check wiring, particularly the hot lead at the blower which is crimped and will drop volts if an aging blower motor is drawing too many amps. That will heat up the connector and melt the wires. Solution is to solder the terminals to the wires. Also check ground - it's shared between the blower motor and the Module. Follow it from the Blower Motor to it's splice with the Module. Also check power at the Module - red - should be battery. Source is from a fusible link or a fuse - depends on Year.
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From: SPRUCE GROVE ALBERTA
On my 90 the wiring diagram says the variable voltage is from the green / yellow wire there is no tan wire from the connectors on the power module, however the serial data to the ECM are tan wires. No change in voltage at the blower power module like it should though....
Le Mans Master
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From: San Diego, Ca
Never seen it that way, but I don't have your schematic. Through
'96, all the inputs I've seen on GM electronic a/c is tan at the blower module. What voltages do you have? Should be 4 wires for your Year. Hot (battery), input, output and ground. Post what they read.
'96, all the inputs I've seen on GM electronic a/c is tan at the blower module. What voltages do you have? Should be 4 wires for your Year. Hot (battery), input, output and ground. Post what they read.
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From: SPRUCE GROVE ALBERTA
c1 connector (2- way) - is the red wire battery 12.4 volts the other position is plugged
c2 connector(4-way) has a purple, green & yellow and black wires with 1 position plugged
purple - has .02 volts if connected to blower motor, with unconnected blower motor - had 6.8 volts
green / yellow has 6.8 volts and voltage does not vary with control head from 1 to 10 speed like the manual says
black 0 volts
Found a source for a new blower power module & will try tomorrow night... what do ya think?
c2 connector(4-way) has a purple, green & yellow and black wires with 1 position plugged
purple - has .02 volts if connected to blower motor, with unconnected blower motor - had 6.8 volts
green / yellow has 6.8 volts and voltage does not vary with control head from 1 to 10 speed like the manual says
black 0 volts
Found a source for a new blower power module & will try tomorrow night... what do ya think?
Le Mans Master
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From: San Diego, Ca
I think you need a new module. I don't have my Manual handy, but isn't one of the tests something to the effect that if the voltage rises with the output disconnnected from the Blower, replace the Module? I would verify the ground and the Blower Connector (look for discolored wires). Ground is shared with the Blower Motor and you should ohm it out between the Module and Blower Motor and then Blower Motor to the frame. NAPA or any GM dealer should have one - universally used across all lines - somewhere around a $100.
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From: SPRUCE GROVE ALBERTA
Is the blower motor suppose to be grounded to the frame (not at the connector but the motor itself)? Mine is attached to the housing which looks like it is something other than metal. The connector ground is OK.
Le Mans Master
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From: San Diego, Ca
As far as I know yes - below the blower motor with the lead at the splice which is wrapped up in the harness. Ground location(s) for your Year should be shown in your Manual. I'd jumper it to the frame to see what happens.
Also, you might - if you haven't - check the fuse that protects the return signal to the Programmer. It's usually a splice off of the blower motor hot lead and then through a 5 amp fuse. I believe it's labled MDL on your Fuse Box, but check your Manual.
I did take a look at my diagnostics and if there is a voltage rise to greater than 6 volts with it disconnected, the manual says to replace the Module.
Also, you might - if you haven't - check the fuse that protects the return signal to the Programmer. It's usually a splice off of the blower motor hot lead and then through a 5 amp fuse. I believe it's labled MDL on your Fuse Box, but check your Manual.
I did take a look at my diagnostics and if there is a voltage rise to greater than 6 volts with it disconnected, the manual says to replace the Module.
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From: SPRUCE GROVE ALBERTA
I am going to try it this week end. I am on holidays for 2 weeks so I will have more time to work on it. I got a scan tool with Bi- Control to test teh heater cotrol head... But I'll try what you suggested until the scanner gets here.
Thanks for all the help & I'll let you know when / if I get it fixed.
Thanks for all the help & I'll let you know when / if I get it fixed.