[vigsom]

Summary

This is an account of how I encountered a weird issue with fuel indication on my 2007 Suzuki Grand Vitara, and the approach that I adopted to solving it. From whatever I’ve seen , there is no documented evidence of this weird behaviour of a fuel gauge anywhere on the net. The experience shared here would, hopefully, be the first one of sorts. Owners of all cars with single or dual fuel gauges can benefit from this experience.

The issue eventually turned out to be just one of loss of continuity, but the time taken to get to the issue was quite long. Although unscientific, I would still add that sometimes solutions don’t pop up when one wants them to. There is a time for everything to happen.

Background

I’ve been holding a 2007 Suzuki Grand Vitara AT for close to 7 years now. Of all the cars I’ve held this far, this is the one I’ve held for the longest time; plus I'm the owner that has held this particular car for the longest time. That is purely because the car has

a) been with me through many ups and downs
b) proven its mettle on several occasions, especially in big deluges
c) been a reliable performer throughout save replacement of ageing parts

Yes, this car has also seen uncommon issues eg. a torque converter clutch input cable getting clipped by mice, ABS hydraulic unit leak, which have been documented in moderator @Samurai’s thread on the Grand Vitara

1. TCC cable clipped by mice (The First Grand Vitara on Team-BHP).
2. ABS Leak (The First Grand Vitara on Team-BHP).

Weird behaviour of the fuel gauge

I’d left the car shutdown for two months and had mothballed the car adequately. When I returned, I performed the following visual inspection

1. Engine bay – check
2. Cabin - check
3. AC filter – check
4. Battery – check

The battery was left disconnected and post return, I found the voltage quite good at 12.4V, not 100% charge but still good enough to start the car. I connected the battery, performed a throttle body calibration (ignition on - pedal down - few seconds - ignition off - few seconds - pedal up - wait 2 mins- start car) and she fired up without fuss. However, when the ignition was turned on, I noticed that the fuel gauge rose only upto E and the low fuel warning light lit up.

Exactly 60 seconds after the engine was started, the fuel gauge dropped back to below E and the warning light disappeared. Watch this video. Engine starts at 0:07 and fuel warning light disappears at 1:07.

https://www.youtube.com/watch?v=PLORc4yn1fg

I knew that the fuel gauge was at approx. 30% before the car was mothballed so there was no reason for this indication to go low, and then out. I filled up fuel for some INR 1,500 but the behaviour persisted.

[vigsom]

Approach to problem solving

The first thing I did after encountering this issue was to refer to the relevant wiring diagram in the service manual. Here are some relevant pages from there.

Wiring layout showing the various couplers – L refers to floor harness (inside the car) and R refers to fuel pump wires




I then embarked on tracing the entire wiring for the fuel gauges from ECM coupler E23 pin#24 all the way to sub-fuel gauge coupler R03, and wanted to focus more on bits on the outside of the car, since these were the vulnerable points to rat attacks.

Tracing the wiring

This inspection took 3 hours, and needed me to trace the wiring couplers from inside the car to the outside. Some of the observations needed me to go under the car, which I did with glee . Actually, I’ve always got under the car at alignment pits to do an inspection of the underbody, but this time, it required me to place a mat and actually slide under the car to inspect.





Based on the above diagrams, I set out to locate and inspect wiring at E80 - L01, L15 - R01, R02, R03.

Inside the car

All wiring was observed intact.

Coupler E80 - L01 at the top of the BCM just above the accelerator pedal


Wiring bunch leading to coupler L15 - this is behind the rear right quarter panel. Access to this part is possible by opening the right side plastic panel just below the parcel shelf. The yellow-red wire goes to the main fuel gauge



Under the car

Coupler L15 - R01 attached to the fuel tank


However, a) R02 viz. the coupler leading to the fuel gauge and fuel pump assembly and, b) R03 the coupler leading to the sub-fuel gauge were not reachable since the gap between the top of the fuel tank and the bottom of the floor pan is just a little over an inch. All I could manage was to raise the mobile camera to its limit and shoot two pics of a part of the fuel tank top. The fuel tank top, was therefore marked as NOT INSPECTED.

Shots of the fuel tank top






The fuel tank on the Grand Vitara is kidney shaped since the rear propeller shaft runs under it. There is no access to the fuel gauge from under the rear seat. I understand that except Maruti and Suzuki, all manufacturers provide access to the fuel pump top from under the rear seat. Removing the fuel tank for inspecting these two couplers was going to be painstaking, and hence I looked at this option only after eliminating all other possible faults.

View of the fuel tank from the bottom (pic courtesy Mod @Samurai) - - the compartment marked red houses the fuel pump and main fuel gauge while the compartment marked green houses the sub-fuel gauge


In the engine bay

I then moved to the engine bay and traced the wiring from the firewall all the way to ECM coupler E23 and found everything intact

Wiring harness near AC low pressure pipe


Wiring between frame and firewall


Battery base plate


Battery base plate removed


Wiring harness below battery base plate


ECM input coupler E23


ECM couplers E23(Grey) and C37(Black)


Most technicians that I’ve known suspected the fuel sensors in the tank, but my old electrician, Jayeshbhai from Navsari didn’t doubt the fuel sensors since he had an experience with an Ertiga where the owner brought the car and the fuel sensor to him for fuel sensor replacement, but the issue turned out to be with the Body Control Module (BCM).

[vigsom]

Next 3 months

I’d meanwhile got busy with other stuff and so decided to let the car run as-is and parked the issue for later. I used a rather primitive method to track fuel in the tank by using a card similar to one used by doodhwalas (milkmen) . Since I wasn’t using the car much, this worked fine for me till my head was ready to get back to solve the issue. All this while, the car ran absolutely fine.

My "Doodhwala" Card


April 2021 – the Mahurat is fixed

1. Inspection of Instrument Cluster

I got back the josh to look at next steps to solving this problem and first inspected the instrument cluster. A local solution was to disconnect the instrument cluster coupler, and reconnect it after 20 minutes or so, just to see if any possible issue inside the cluster was responsible for this fuel gauge error; no abnormality detected (NAD).

Instrument cluster cover removed


Instrument cluster coupler intact


Fuel indicator error even after disconnecting for 30 minutes and then re-connecting


2. OBD scan

An OBD scan threw up this error P0463 viz. Fuel level sensor circuit high (voltage)


The service manual recommended some steps to get to the issue, as outlined in the attached pictures



The steps outlined here pointed to chdcking for loss of continuity, and I had already inspected all the wiring, save the one at the top of the fuel tank . Now, the only step left was to inspect the fuel sensors and the associated wiring. However, as already outlined earlier, removing the tank was a difficult task, but had to be executed. There was no other option left.

[vigsom]

April 2021 (Contd.)

3. Inspection of the Fuel Tank top

Removal of the fuel tank required the silencer can and the rear propeller shaft to be removed. However, bolts on the silencer can were tight and therefore the rear half of the silencer (including the can) was removed as one unit. The unit, although 14 years old, was in top shape.

Next, the rear propeller shaft was removed, and then the tank connections (fuel inlet, fuel pump discharge, fuel pump return, fuel pump vapour line) were removed. The Tank, in my estimate, had approx. 30 liters of fuel, and a jack was used to lower the tank.

Silencer and rear propeller shaft removed


Picture of the underside with fuel tank removed - as clean and corrosion free as it can get


Fuel tank side view


Silencer assembly in good shape after 14 years


Fuel supply, return and vapour lines





Culprit identified

There is this 1996 Hindi movie called Yeshwant in which famed actor Nana Patekar delivers a very popular line about how a mosquito (ek machhar) made a man look like a fool. On similar lines, this time, a rat (ek chooha) made me feel powerless. How and why this rat chose this awkward, tight spot, to sit and cool off is beyond my comprehension, but then, try as hard as one wants, one can’t comprehend Rat Logic.

Wiring to the sub fuel gauge chewed off




I observed that the wiring to the fuel pump had some protection in the form of a sleeve, and the rat had even gnawed at it but didn’t cut through. As a long term action, I decided to have some wiring sleeve installed on the entire wiring on the tank top.

Fuel tank wiring - stock with sleeve on wiring to the fuel pump


Fuel tank wiring - reinforced with sleeve all over


Once this job was done, the fuel tank wiring coupler R01 was coupled to coupler L15 and the ignition was turned on. Bingo !!! The gauge was reading and showed a little over 50% (that was my estimate of fuel in the tank).

The tank was then re-installed and next came the rear propeller shaft and then the silencer.

Time and Money

I spent close to 32 hours on-the-job and several hours thinking about what could have happened. However, in money matters, I got away with an expense of just INR 1,000.

Key learnings

1. Never underestimate the power of a common rat
2. With the Grand Vitara, ensure that mothballing also includes protection of the fuel tank top with some repellent
3. While the issue was simple, and could have been closed by directly attacking the tank, I chose the longer systematic route to eliminate other possibilities
4. Unless tampered with, the wiring and components in the Grand Vitara withstand the test of time. The car's quality is top notch
5. Common thought when faced with an issue like this is to attack the fuel sensor first - it is better to inspect wiring first before getting to the tank

All's well that ends well !!!

[GTO]

Thread moved from the Assembly Line to Tech Stuff. Thanks for sharing!

Will go to our homepage tomorrow .

[gkveda]

A good suspense thriller story on Saturday morning.

I too suspected the sensor initially while reading the story. Especially, when the light goes off Automatically at 1.07 sec in the video.

I think, for issues like this, it is better to connect a parallel wire between source and destination and check if the issue gets resolved. If it gets resolved, then directly we can come to a conclusion that connecting wire is the culprit and proceed with investigation in that direction. Probably this saves lot of time and effort.

Usually, car electricians connect a bulb- battery circuit such that the suspect wire is a part of the circuit. If bulb does not glow normal, then suspect wire is concluded as faulty.

[anandpadhye]

Wow. Kudos to your diligence.
I would have just taken the car to the service center and asked them to check. Back in 2008 I bought a used Tucson and the airbag warning lamp was always on. Left her at the service center where they did similar painstaking due dilligence and loacted the wire that was cut, rather than blindly replacing airbag sensors.

Grand Vitara is a lovely SUV - I so badly wanted to buy one when it was launched but did not have the budget. Even after so many years, GV still looks good and whenever I see one, the itch comes back

Great to know that you have held on to her for over a decade and she has been reliable. Long term ownership has it's own charm, especially in this BTST (Buy Today Sell Tomorrow) market of ours and there is so much to learn from such threads.

Wishing you many more kilometers with the GV!

[Jeroen]

Excellent job. Great trouble shooting. Very methodical.

As I have been saying for a very long time; So called “electronic” problems are rarely electronic problems. 95% of these sort of weird and annoying problems tend to be simple mechanical/electrical problems. A broken wire, a dirty connection etc. Finding them can be a real royal PITA. Kuddo’s to your perseverance.

A few additional thoughts:

Its not always possible, but it makes sense to always check for error codes before commencing any trouble shooting. It can save you a lot of time.

When checking for continuity it is best not just to check for visuals, but get a multimeter out and measure continuity as a low resistance across wiring, connectors etc.

You don’t mention it specifically, I assume you probably did anyway.

Always disconnect each and every connector and ground strap you come across. Open them up, check very carefully for loose pins and or corrosion.

Rats/rodents can be a real menace. Again, job really well done!


Jeroen

[sridhar-v]

Originally Posted by vigsom

2. OBD scan

An OBD scan threw up this error P0463 viz. Fuel level sensor circuit high (voltage)

Which OBD dongle are you using?

BTW you have a knack of photographing and documenting all the steps. I am too lazy to take such pains.

[Crow]

@vigsom My respect for your knowledge and scientific approach just keeps growing with each new thread. Kudos.

PS: I hope you managed to clean that fuel tank before replacing it. Saw how grimy it’s become thanks to almost 15 years of usage and I felt like cleaning it immediately.

[Malluspec]

Just asking out of curiosity, couldn’t you have directly checked the continiousity of the wiring from the fuse allocated for fuel pump directly so as to ascertain a wire cut instead of painstakingly inspecting every inch of the wire?

[W.A.G.7]

Awesome effort, man! That was a systematic and a stepwise way to solve a problem. I guess you saved quite a lot of bucks there as well. If you had gone to any garage (Maruti or Otherwise), that would have set you back by a couple of thousands. That's why I love Team-Bhp, there are so many enthusiasts in their own way, willing to share their knowledge in the open forum!

[vigsom]

Originally Posted by gkveda

better to connect a parallel wire between source and destination and check if the issue gets resolved.

Originally Posted by Malluspec

couldn’t you have directly checked the continiousity of the wiring from the fuse allocated for fuel pump directly so as to ascertain a wire cut instead of painstakingly inspecting

Good suggestions, @gkveda and @Malluspec. Knowing that components in this car are top notch and not likely to fail, I could have decoupled coupler L15 - R01, and checked for continuity of the line all the way to ECM coupler E23 pin#24, and then wouldn't have had to inspect any of the wiring on this path. That would have left me with just two culprits - the tank top and the instrument cluster.

I followed the longer path just to ensure I left nothing un-inspected and to also understand the wiring layout as part of learning.

Originally Posted by anandpadhye

I bought a used Tucson and the airbag warning lamp was always on. Left her at the service center where they did similar painstaking due dilligence and loacted the wire that was cut, rather than blindly replacing airbag sensors.

Thank You @anandpadhye. These days, most service folks just go ahead and replace stuff instead of taking trouble, but there are some technicians like Avijit in Hyundai dealership in Kolkata who still do painstaking diagnosis.

Originally Posted by Jeroen

Its not always possible, but it makes sense to always check for error codes before commencing any trouble shooting. It can save you a lot of time.

When checking for continuity it is best not just to check for visuals, but get a multimeter out and measure continuity as a low resistance across wiring, connectors etc.

Always disconnect each and every connector and ground strap you come across. Open them up, check very carefully for loose pins

Thank You, @Jeroen, for those tips. I was supremely confident that I'd get to the culprit, but also knew that I needed to be systematic and patient.

I was wanting to first perform a scan and then go about the diagnosis, but then decided to inspect the obvious first, since I'd seen a rat in the bay before I mothballed the car. Both in 2017 when a rat had clipped one cable to the automatic transmission and this time, it was winter time and rats would look for cozy places to sit.

Yes, I did check for continuity when I traced the wiring. Also, I decided to go the tough route of tracing the complete wiring (including inside the car) just to understand the layout better. Who knows, this learning might help me solve a bigger issue tomorrow for someone.

Originally Posted by sridhar-v

Which OBD dongle are you using?

Thank You, @sridhar-v. This was a Launch dongle and the software was on the garage owner's mobile phone. I know the bloke and had requested him to perform the scan.

Originally Posted by Crow

I hope you managed to clean that fuel tank before replacing it

Thank You, @Crow. I got the tank cleaned on the outside, but didn't get the inside inspected, since I trust the fuel I've been putting in this far

Originally Posted by W.A.G.7

If you had gone to any garage (Maruti or Otherwise), that would have set you back by a couple of thousands

Thank You, @W.A.G.7 . A service center would have told me this

1. Replace main fuel sensor and sub-fuel sensor
2. Replace Instrument cluster
3. Interior disinfection and treatment
4. Replace wiring harness from coupler R01 to R02 and R03

It is like asking for a leg to be replaced when there is just a torn ligament.

[Raghu M]

What a thread. I read it like we watch a Netflix thriller. Just amazing to see your patience and the determination to get to the root cause and fix the problem. If this happened to today's cars, let's say the fuel gauge shows empty, would the distance to empty be wrong too then?

[RGK]

Originally Posted by vigsom

Thank You, @W.A.G.7 . A service center would have told me this

1. Replace main fuel sensor and sub-fuel sensor
2. Replace Instrument cluster
3. Interior disinfection and treatment
4. Replace wiring harness from coupler R01 to R02 and R03

It is like asking for a leg to be replaced when there is just a torn ligament.

very true.
I had a similar type of experience when a malfunction light was ON while starting the car. The SA gave a direct solution to replace the entire wiring for Rs 17000/- (for my Figo) and advised me to claim through insurance.

Luckily I take the help of an expert in this kind of issue and he identified a rodent bite near the turbocharger boost sensor and sealed it with ten-rupee tape. The issue was solved in a quick amount of time for a nominal labour fee of Rs 500/-.

You have a done a meticulous job .