Blower motor doesn't work
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Cargo Master
Joined: Oct 2018
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From: unfortunately Germany
Is this on the trans tunnel inside the truck?
Hotshot
Joined: Dec 2014
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From: Jersey Shore
Yeah, that's what I was getting at. If there is resistance in the circuit, volts look fine with a voltmeter, but with a load, the voltage can drop. You have speed controller, which adds another variable.
And the blower is the biggest single load in our trucks after the starter and glow plugs.
And the blower is the biggest single load in our trucks after the starter and glow plugs.
Fleet Owner
Joined: Nov 2003
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Mark, G104 is the only ground point shown in the manuals between power sources (battery and alternator). The other two braided wires (12ga) are not shown, and are called out as bonding cables, but are never noted in the diagrams. Which makes people believe they are inactive. They are not. They add a good amount fo the current flow, and are bi-directional depending on starting vs running.
Remember, I'm an electron flow guy, not a current flow guy. When people are trained in current flow, they overlook the negative side connections. Going by the manual diagrams only, this is missed.
By the diagrams, positive flow goes from the positive battery post to the CJB by a 4ga cable. By the diagrams, negative flow goes through the 8ga negative battery post connection to the inner fender. That does not add up and restricts (8ga resistance) the voltage through the 8ga cable. 8ga + 12ga + 12ga = 4ga.
Remember, I'm an electron flow guy, not a current flow guy. When people are trained in current flow, they overlook the negative side connections. Going by the manual diagrams only, this is missed.
By the diagrams, positive flow goes from the positive battery post to the CJB by a 4ga cable. By the diagrams, negative flow goes through the 8ga negative battery post connection to the inner fender. That does not add up and restricts (8ga resistance) the voltage through the 8ga cable. 8ga + 12ga + 12ga = 4ga.
Also attached is the diagram for the EATC module and the speed controller
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Cargo Master
Joined: Oct 2018
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From: unfortunately Germany
I have a multimeter and a forceps multimeter (don´t know correct word) here. But I am missing the corresponding sharp needles to get through the cable insulation. I will try to buy needles and put them through the insulation so I can read the actual volts. On the regulator Mark wrote, there are a lot of thin wires going to the regulator. I would prefer to run the fan provisionally at mid-range all the way home. Maybe I could make something there... In humid weather I can't drive otherwise, because I can't see anything through the windows.
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Cargo Master
Joined: Oct 2018
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From: unfortunately Germany
thanks Mark. How would you test the controller?
Fleet Owner
Joined: Nov 2003
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Just to be clear, the variable voltage you saw (4-14) was on the BN/OG wire?
Disconnect connector 1031 (BN/OG wire to motor). Are you getting full voltage on that wire when you turn on EATC?
Also, you did verify the relay in the underhood BJB (303)?
Disconnect connector 1031 (BN/OG wire to motor). Are you getting full voltage on that wire when you turn on EATC?
Also, you did verify the relay in the underhood BJB (303)?
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Hotshot
Joined: Dec 2014
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From: Jersey Shore
Mark, that layout is essentially no different than the 2003. G104 is the 8ga connection between the battery and the fender. The 1 of 3 connections between supply and the ground plane (the body tub) that all harness negative side or grounds connect to, with the exception at the tail of the truck.
The body tub is the ground plane. It is supplied by the 8ga cable and the two 12ga bonding cables. From the ground plane, all other electronics are supplied, with the exception of the tail previously noted.
BTW, you drawing notes G102 up by the firewall and the front of the engine. G102 is at the bottom front of the engine block only.
Harwig, you can use a straight pin or sewing kit if the wife is prepared as well as you are. When we would get Mazda test vehicles from their training center, we would find sewing straight pins all over the harnesses.
The body tub is the ground plane. It is supplied by the 8ga cable and the two 12ga bonding cables. From the ground plane, all other electronics are supplied, with the exception of the tail previously noted.
BTW, you drawing notes G102 up by the firewall and the front of the engine. G102 is at the bottom front of the engine block only.
Harwig, you can use a straight pin or sewing kit if the wife is prepared as well as you are. When we would get Mazda test vehicles from their training center, we would find sewing straight pins all over the harnesses.
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Cargo Master
Joined: Oct 2018
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From: unfortunately Germany
i have to check this again tomorrow. i am standing here on a campground and its 11.00PM, so I must be quiet.
I have measured 4-14V on the cable OR/BL, depending on how I adjusted the EATC, connector disconnected!
I have measured 4-14V on the cable OR/BL, depending on how I adjusted the EATC, connector disconnected!
Fleet Owner
Joined: Nov 2003
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That should mean that the motor speed controller is working if I understand things correctly. Check voltage from the BN/OG at the motor (but with the blower motor disconnected) and the EATC on.
Edit - This is step N2 (PinPoint test N) in Sean's (much appreciated) attachments below
Edit - This is step N2 (PinPoint test N) in Sean's (much appreciated) attachments below
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Cargo Master
Joined: Oct 2018
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From: unfortunately Germany
That should mean that the motor speed controller is working if I understand things correctly. Check voltage from the BN/OG at the motor (but with the blower motor disconnected) and the EATC on. Edit - This is step N2 (PinPoint test N) in Sean's (much appreciated) attachments
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Cargo Master
Joined: Oct 2018
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From: unfortunately Germany
I'll try to work it off. Thanks again.