Gas gauge acting up?
- Thread starter setty7
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
SunlitComet
OBS Jedi-Do Good
Awesome....thanx Sun.
Update-- I disconnected the 2 wire plug, and did a resistance test. I'm getting ~4 ohms.
Right now I have 3/4 of a tank
What should the empty/full resistance readings be?
I've heard 40 ohms full/250 ohms empty
and 90 ohms full/0 ohms empty <<<< which is correct??
Alldata specifies for gas engine 40 empty and 250 full. So 3/4 tank full you should be reading 157.5 ohms.
So by bridging across w/a 47 ohm resistor, the gauge should read about empty.
Gauge resets by going to full then settling to it's previous incorrect reading.
I always thought it went to empty first on the reset....but don't recall lookin @ it before.
I think it is the stepper motor.... I'll know when I get the used cluster( I still haven't heard from the sources I contacted about new steppers).
Thnx again Sunlit.
SunlitComet
OBS Jedi-Do Good
Something to keep in mind starting in 1998 gas senders were no directly connected to gauge anymore. The sender goes to the PCM and is processed there before going back out to gauge cluster. That means the pcm now is a factor in the problem and unfortunately there is no tech data to isolate it as the cause except that you have to checks sender and gauge individually. If they and the wiring both check out fine then it would be assumed the PCM is at fault.
DefendHawaii
Snake Eater
I need to look into this as well. When I fill up it goes way over the F part about a half inch over that. Also first time we drove it right before the needle hit the orange it died. luckily I was actually in front of a service station to fill up.
I have a schematic(partial) of the PCM that was posted sumwhere on here. It doesn't show the pathway from the EEprom to the fuel gauge in the cluster, only from the sender to that chip. Does anyone have a complete schematic of the PCM hangin around? '99 OBS
JonnyTahoe
Full Access Member
Mine does the exact opposite of Jc's. hit the brakes it goes towards "E" Accel goes towards" F" then levels off. When tank is 3/4 or higher works like it should. When I run it down to almost empty and come to a stop the gauge will go all the way to "F" and then all the way back down to empty 1 time. What up wit dat?? JT
After doing extensive research on fuel gauge problems for our trucks, I came across this @ another site.... http://www.pacificp.com/forum/viewtopic.php?p=93001&sid=2943b29b08c9eece5fe115ef9747eba6.
It's a 13 page thread, but ultimately it says that GM uses a dampening fluid in the fuel gauge motor, and because the units are not sealed...it leaks out, causing the Hummingbird effect w/the fuel gauge. Apparently they send the voltage from the PCM to the gauge, and it contains a 60hz pulse. The fluid is supposed to keep the needle from vibrating from the signal.
I got my used cluster in today, and still have the hummingbird effect w/that one(it does have over 100K on the clock tough).
I'm going to pull apart the spare cluster, remove the fuel gauge, and investigate.
I'll post any positive findings.
It's a 13 page thread, but ultimately it says that GM uses a dampening fluid in the fuel gauge motor, and because the units are not sealed...it leaks out, causing the Hummingbird effect w/the fuel gauge. Apparently they send the voltage from the PCM to the gauge, and it contains a 60hz pulse. The fluid is supposed to keep the needle from vibrating from the signal.
I got my used cluster in today, and still have the hummingbird effect w/that one(it does have over 100K on the clock tough).
I'm going to pull apart the spare cluster, remove the fuel gauge, and investigate.
I'll post any positive findings.
SunlitComet
OBS Jedi-Do Good
Normal with non full tanks. The lower it is the worse it gets. They really don't have baffling that keeps the fuel from wondering around.
---------- Post added at 03:18 PM ---------- Previous post was at 03:16 PM ----------
Glycerine is the most common damping fluid used.
Well after a bid of tech. work w/my vibrating fuel gauge..... it is definately the gauge/motor itself.
Has anyone ever found out where to get just the motor (new) for the fuel gauge ('99 OBS Tahoe)??
I know it's an extremely well guarded secret, but I'd hate to spend the big bucks, and send out my whole cluster for something that I can change out in less than 1 hour myself.
Has anyone ever found out where to get just the motor (new) for the fuel gauge ('99 OBS Tahoe)??
I know it's an extremely well guarded secret, but I'd hate to spend the big bucks, and send out my whole cluster for something that I can change out in less than 1 hour myself.
