fuel guage goes to E when lights turned on

[86chevyk20]

My fuel guage seems to be acting a bit strange. my guage does work but sometimes if you tap it, it bounces around. And this is werid, when i turn my lights on the guage goes to E and when the turn signals are on the needel twitches.



This is strange

 

[RetroC10Sport]

Sounds like a printed circuit and/or ground problem.

 

[elstm3]

I would say ground issue also. It could also have a bad or weak connection from the posts on the gauge to the back of the gauge cluster. in my brothers s-10 the fuel gauge goes to empty and back to the level when you turn the blinker on . and goes empty when the lights are on.

 

[flyguy_17]

My 85 K30 just started doing the exact same thing a couple weeks ago. Gas Gauge reads normal until I turn the lights on to either clearance lights or full headlights. Also, the right blinker light in the dash comes on solid and stays on and most of the instrument panel is black. With the switch in the clearance lights setting, the high beam headlight indicator is on. I'm guessing it has to be a ground on the printed circut board. Anyone know of a good place to get replacement circuit boards?

 

[RetroC10Sport]

LMC truck has some.

 

[zieg85]

I had the same exact issue with my 85 C20 when I first got it. It turned out to be the printed circuit board on the back of the speedometer cluster. I went to the local pick and pull and harvested one off a nice Suburban with a quartz clock for $35.

 

[Dyl0116]

My fuel gauge acts as a flasher when the right signal comes on.. needle bounces down to less then e, then when signal is turned off, guage slowly climbs up..

 

[Oregon78k10]

I literally just had this happen to me tonight... but my left blinker indicator stays on aswell..lol

 

[roadtriper]

Everyting here sounds like ground issues to me. which can also be poor connections on the back of the cluster as well I'd first check the grounds for the front lights at either the fenders or the radiator support.and make sure there is a good Battery to Frame ground and a good frame to body ground. 25+ years of corrosion can do bad things

For the brother with the S-10 there is a ground wire under the dash to the left of the steering column(10mm head) that comes loose and will cause all sorts of demonic things to occur with lights, the radio , guages etc.

Back to the C/K
the gauges are atatched to the circuit board with spring clips and sometimes will get a loose connection with the circuit board and or the posts on the guage. they can be removed, cleaned and tweaked to tighten them up. also the ceramic resistor on the back of the gauges has a silver printed circuit that tarnishes and can be cleaned up.

best method to find bad grounds is performing a "Voltage Drop test" with a Volt meter with the system powered up and perferably the fault occuring.
take the neg test lead at the neg post of the battery and touch the positive test lead to the engine block, the frame, the body, the component etc. if you see more than .2-.5 volts you have a poor ground. i.e it's trying to find a better ground through your meter. you can take you 2 test leads between any 2 points as well like the frame to body etc. this can be done on any connection or any circuit positive or neg. but the system needs to be loaded.
rule of thumb is you'll have a max .2 volt drop for each connection and a .3 volt drop through a switch or relay.
when in doubt... run a redundant ground to the component acting up and see if it corrects the problem? you cant have too many grounds! RT

 

[foamypirate]

...RT

Great info! Thanks RT!

 

[83swb]

RT

Awesome writeup, cleared up why I have no left turn signal, taillights, or fuel guage

 

[roadtriper]

Also there is a ground wire from the fuel gauge sending unit(s) that atatches to the Bed or maybe the frame that needs to be clean and tight