I'm sure I got a short.

[Curious Hound]

I got my EVTM Book today now I just got to learn how to read it.

There are several good sections near the front that actually explain how to use the book, plus other useful information. You may also find this useful.

 

[ShhhhhDougsHere]

Well " Curious Hound " I enjoyed that video and thank you for it.

 

[ShhhhhDougsHere]

Okay " Curious Hound" my gas gauge has not worked properly since I got the truck.
I don't want to go through all the trouble of removing the instrument cluster to get to the SLOSH MODULE if I don't have to.
I want to see if there is a signal coming from the fuel pump first.
However I don't want to lift the bed to get to the fuel pump if I don't have to.
So in my EVTM on pages
61-2

150-3

151-3

I find connector C118.

My question to you is if I disconnect that connector (C118) then put a pin in the female side at Port four wire 29Y/W. Then connect my test light alligator clip to the pin. Then touch the pic end of the test light to Port four wire 29Y/W on the male side. If my fuel pump is sending a signal towards the gas gauge. Should my test light, light up?
Or does it not send enough power throw that wire to light the light.

Am I on the right track?
Should I use my multimeter instead of the test light?

 

[Brain75]

From the pic right there, it says that (wire 29 - Y/W, pin #4) is the variable ohms line from the sender, not the pump. So I would hook up a test meter set to ohms, and read the what is coming from the sender (red probe) to ground (black probe to body frame).
Not sure why the manual has the ohms range say what it does but just about all Fords are 16-160. If your tank if about half full expect a reading of roughly halfway between 16 and 160 - what ?72? if my mental math is reasonable..

To test the gauge and not the sender, when you unplug C118 the gauge (now infinite restistance) should be "past Full", if you short that pin to ground you should get "past Empty" - hold it for several second to get past the anti-slosh module's "averaging out" and the needle to change. That side needs key on during test though to have power to the cluster.

 

[ShhhhhDougsHere]

Okay now the OHMS setting is the one that has a symbol that looks like a set of headphones?
If I'm right I have the red probe pointing to the symbol in the picture right?

 

[Brain75]

yup, and it looks like you meter is capable of all kinds of ranges within the umbrella ohms... set it to the lowest - 600 (2 below your probe) - since you want to be able to read 16-160 expected figures.
(Setting it to like the 6000 or 60 million makes it too numb to read usefully.)

 

[ShhhhhDougsHere]

First Brain,
Thanks for taking the time to help me understand.

So I want to make sure I understand this right.

First I carefully unplug the connector.
I then set the multimeter to the 600 OHMS setting.
Then I put black probe on a good body ground spot.
Then with key on,
I try the red probe to pin 4 of each side of the connector.
That way I know I'll get the right side.
Once I get a reading I'll know that is the right side of the connector.

If I don't get a reading on either side I know I need to lift the bed right?

 

[Brain75]

Don't need the key on to test the sender - in fact you can test the sender on the bench / out of the truck with no power what so ever, it is a dumb variable resistor (rheostat) that changes resistance depending on the position of the float arm.

Pretty easy to figure out the correct side - the portion of wiring that goes through the firewall and into cockpit is going to be the dash end, the portion of wiring that disappears down towards the transmission running along but outside the firewall is the part that goes to your fuel sending unit.

 

[Brain75]

And fwiw, you are only going to get one figure - either a good figure which is relatively close to how full your tank is (somewhere between E/16 and F/160) or a bonkers figure (less than 16, greater than 160). If you leave that hooked up and have a buddy go gorrilla trying to rock the truck enough to slosh the fuel around you might see if fluctuate - your gauge might not be fast enough to really read that though...

 

[ShhhhhDougsHere]

Okay.
Thanks once again.

On to the next question.

If I do get a good reading,
then I know I need to pull the instrument cluster and check the SLOSH MODULE right?

What's going on is when my truck is turned off the gas gauge reads about a 1/4 tank.
Most of the time once I start it the gas gauge then reads empty.
However sometimes it will read anywhere above empty. <---- however that's rare.

 

[Brain75]

That sounds like slosh module for sure. when they go bad, typically (not always) you get a bogus empty reading.

If it is PAST empty or PAST full - like 2 needles width gap, then it is an open or a short (which to test the gauge that is what you do - unhook the connector entirely causes an open, short pin 4 on the cluster side causes a short).

 

[ShhhhhDougsHere]

Okay if I understand your last post right,
Once I unplug the connector we've been talking about the gas gauge will move one way or the other?

 

[Brain75]

yes, unplugged it is no longer getting any resistance from sender (so infinite resistance to ground), anything above 160 ohm and it should read past full (or past empty - but referring to your picture 61-2 I think I got that correct)

 

[ShhhhhDougsHere]

So if I understand right it moving at all tells us i.e. me it is getting some kind of signal right?

 

[Brain75]

yes and no - moving at all says that either it is getting a valid signal from the sender or an invalid signal from somewhere else (slosh module)/short/break... hence all the testing.