I have a '95 GA 2.3 4 cyl. with four spd auto.
It also has 132,000+ miles.
It showed up last night with Code "29 Quad Driver Fault D" I'm more or
less set on replacing the ECU but wonderered if anyone thought
From what I read a Quad Driver is sort of like a partition on an old PC.
In a sense anyway. I also read both that the ECU is the fix, and that
something outside, like a short, will cause a quad driver fault.
The only recent things to maybe consider is that we had pretty good
rainfall all day before this code showed up. Also, a few weeks ago the
front window motors were replaced.
Any ideas appreciated.
A quad driver has nothing at all to do with partitions on old PCs!
You know what a relay is? Well, if you take the solid-state version of a relay,
that is often called a driver. If you put four units of that into one module,
you have a quad driver. Often these are found as a piece of the car computer,
and that is what "turns things on and off", to put it bluntly. If you have a
short circuit on a load, e.g. a window motor, you might blow one part of a quad
Thanks for the link Paul. Thanks for the info Bob. I learned a lot
researching this. I did not change anything including the ECM. I did
remove it and the PROM from the ECM believing I would purchase a new
one, but backed out and reinstalled the old one. It's never happened
again. So, I'm just going to chalk this one up to the extremely heavy
rain possibly shorting a power window relay, and just wait until it gets
worse or shows up for good. It can't be fixed until it's broke.
For future reference, does anyone know where to look to see what each
quad driver controls? For instance, mine said quad driver fault D. So I
take that to mean that quad driver D faulted. Whatever it controls.
Back in '91, I purchased my first GM car, and immediately I ordered the Helm
manual for it. The Helm manual shows virtually everything that a shop
technician might need in diagrams, schematics, and description. So, it goes
into the detail that you need. Later on, I moved from that GM car to a new GM
car, and I got the Helm manual for it. In fact, somebody asked me if I had my
used Helm manual for the '91, which I did, so he ended up buying it from me. To
some owners, a Helm manual is worth its weight in gold. At a minimum, it is
worth several times its considerable cost.
Hi all. I have gotten the same problem with a 1993 Grand AM 2.3 Quad4
SOHC. The interesting thing here is I replaced my front window motors
also. From what little I understand about this code, a short can cause
this to show up. This is highly possible in my case. When I was removing
the Rivets that hold the power window motor regulator in place, I cut in
to the power window wires. I thought I had fixed them pretty good, but, I
guess I will have to check again. My question is... If this turns out to
be the case, and I fix the wires, has irrepairable damage occured to the
computer already? Might this just be coincidence that both of us relaced
the window motors? If so, what is the first course of action here?
Replace the ECM? you can directly get to me via email at richard.tawney
I can't see this being related - the quad driver code indicates either that
the quad driver in the ECM is bad or that there's a short on one of the
outputs that the quad driver controls, and the ECM is not connected into the
power window circuits..
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from firstname.lastname@example.org
RH says that the computer is not connected to the power windows, but
either that is wrong, there is a very strange coincidence, or
electricity has a funny way of making travel. Reason I say this is in
late March or early April I had my power windows replaced at my dad's
shop. Interestingly, the very next day I got code 29, quad driver "D"
fault on my '95 Grand Am.
I extensively researched this subject afterwards, and reset my computer
to see if it would happen again. It never has happened again. Also, on
older computers it would permanantly damage the computer but on newer
ones they simply shut the circuit down and try again. I'm sure you don't
have any damage on your '93, although I'm sure it's possible, but not
On Fri, 21 May 2004 20:37:47 -0500, email@example.com (Tony
I have to agree with Mr Hancock on this one. The quad drivers have
nothing to do with power window operation on that vehicle. Either
pure co-incidence or the shop screwed up something else by accident
while fixing your windows.
I had a similar problem with a GM 3.8 -Quad Failure code- turns out it
was the EVAP canister -shorted coil.First thing to do is get a
electrical schematic and trace out what devices derive power from the
same fuse that powers the ECM Quad Driver Circuit that is giving the
code-there are usually several Quad drivers in the ECM.
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