WillieD

Does anyone have a wiring schematic for the MAF for an 02 F-body? More specifically, I am trying to figure out where the black/white wire on the MAF runs to. Does it run directly to the PCM or does it pass into something else? I am getting a lot of resistance on this line (over 30 ohms), and it is beileved that this is the reason my car has been running like crap. My car has been throwing P0102 and the MAF keeps failing at randon according to the Tech II. It all happened after I sat in traffic for nearly 2 hours one day. We are thinking that somehow the black/white wire is damaged/has a short somewhere and is causing my problems.

Any help would be appreciated to get this figured out. I have been fighting with this for over 2 weeks now and it is really getting old. I just want my car to run right so I can take it to the track!!!!!

Another_User

It is ground.
Yellow is signal to the PCM.

WillieD

I know it is a ground, but does it need to ground in any certain area? Looking at the holden info from above in this forum it shows the ground wire running to a ground and to the PCM. Check out page 40 of this link:
http://carprogrammer.com/Z28/PCM/LS1/Holden_LS1.pdf

The yellow wire is giving me the 5v it should and the pink has the 12v like it should. We had a lot of resistance with the black/white wire and I am trying to figure out the remedy. We ran a fresh ground wire to a chassis ground and it did not make it run any better.

jimmyblue

iTrader: (11)

https://ls1tech.com/forums/showthrea...44#post1141944

Black/white is supposed to be block/chassis ground. If you measure
any ohmage from the MAF connector to shiny metal, something is
messed. Check for a missing/loose/busted block-chassis ground strap,
is my guess. The Helm book indicates it is a star ground to the same
(S110) point as the PCM. If there is a problem here it could cause
all kind of mischief.

WillieD

where does the PCM ground out at?

Speartech

iTrader: (14)

The bolt on the back of the cylinder head.

jimmyblue

iTrader: (11)

G110 appears to be a bolt into the backside of the driver's
cylinder head. S110 is a connection inside the main engine
harness bundle 8" from the "PCM breakout".

I would check those G110 ground bolts and the straps that go to
them.

WillieD

Oh, in a very convenient spot. I am assuming it is on the passenger side head...

but wouldn't a new chassis ground solve any issue I was having there?

jimmyblue

iTrader: (11)

Not if the block has "come loose" electrically from the chassis,
high electrical load can jack the "working" ground apart from
the "reference" ground. Then lots of signals pick up large
bogus offsets.

WillieD

i can see all of that stuff, and it all looks good. It is kind of hard to tell being behind the motor though. The bolt is snug and there are a few main wires leaving it going into the main wire loom. I followed the black/white wire back to where everything comes together and it all looks good up to there.

WillieD

when I use the voltmeter and touch the maf plug and the wire behind the block I get a connection. I don't know where to go from here.

WillieD

I also used the voltmeter and I am getting a connection from the MAF to that bolt on the back of the head. I don't know where to go from here

WillieD

I am no electronics expert, so explain this to me. I set the voltmeter to buzz and touched the plug for the black/white wire to a chassis ground and the engine ground and got a buzz. I also touched it to the pink wire and got a buzz in both locations. The ignition is off and I am not getting any power to the MAF. Should I be getting a buzz on the voltmeter from the pink wire to a ground?

jimmyblue

iTrader: (11)

Run the engine with full accessory load and measure block
to chassis, block to TPS black wire (PCM ref), and block to
MAF black/white wire (plugged in). Use a sewing needle or
something to get to the wire conductor. Use a low voltage
scale if you do not have an autoranging DMM. You want to
see no voltage differential anywhere. If the block is offset
from the sheet metal then maybe it's the other end of some
block-chassis braid strap that's loose. If all grounds are good
and tight with each other then you have to look elsewhere
for the error.

WillieD

what am I supposed to measure from the block to chassis, block to black/white wire, and the block to the tps? Ohm's? If it is Ohms I am screwed because I can not figure out how my buddy's voltmeter reads ohms.

Also, which wire is the TPS?

jimmyblue

iTrader: (11)

DC Voltage, you want zero voltage ground-to-ground
even with the full electrical load. That tells you it's
solid and everybody should be on the same page
(so to speak).

Beeper is handy but it may not know the difference
between a milliohm and an ohm, but put 10 amps
of engine actuators' drive current through an ohm
of crusty ground-screw and Toto ain't in Kansas no
more.

WillieD

OK, I got the voltmeter to work on measuring ohms (the needle was getting stuck and would not move all the way). I did it from the engine ground to the chassis ground, as well as from the black/white wire to the engine ground and it all looks good. The other day I was getting a lot of resistance using one with a digital readout. I will try and get my hands on that other one tomorrow and test it again.

WillieD

there was zero voltage between the grounds

jimmyblue

iTrader: (11)

Then the ground situation (if there was any) is
not the problem. If the MAF is getting 12V power
and 5V load pullup then that's all it needs. Does this
meter read frequency (Hz)? That would tell you if
MAF, being properly supplied, is alive or dead. Look
for 2500Hz riding on the 5V (yellow) wire. If it does
not read frequency, hook the meter up in voltage
mode and look for a slight decline in the "5V" value
as you rev the motor (foot-stall it, would be best
but maybe inconvenient).

If this all pans out normal, maybe it's just a ghost.

What was the original problem, again?

WillieD

The original problem is the car bogging down and running like crap. It usually idles fine, but when accellerating either slowly or fast it will jump violently and buck. The fuel pressure does not drop and the Temperature sensor does not change either. Sometime it does it while cruising too. I am sure it is not good for the motor to keep doing that.

We were using a Tech II and it does not have a setting to read in Hz. I will check the 5v fluctuation tomorrow. I don't think the people in my apt complex would like me revving my car right now

The reason I have been messing with the MAF the whole time is that the MAF "Fails" according to the Tech II everytime my car has the problem. I have not been able to tell if the power to the MAF has fluctuated while the motor was being revved.