Fuel level reading not correct, what's up?

[91 318is]

Half full is the new full.

Deal with it.

best advice so far in this thread, lol.

[91 318is]

bringing this back up.

So I got another known good cluster out of a 318is, swapped it in with my code plug and the gauge is still reading the exact same as the other one.


I'm COMPLETELY out of options now, I don't know what else to try out.


Is there any way it could be the coding plug or does that have anything to do with the fuel indication at all?

[Jean]

Test sender with ohm meter yet?

[91 318is]

Test sender with ohm meter yet?

No not yet. I put a brand new sender in so I wasn't thinking that would still be the problem. I guess I need to check it for the hell of it.

[91 318is]

No other advice?

[91 318is]

I wanna clarify something if anyone can help me out.

If you swap a late model fuel gauge in a early model cluster, will the gauge still read wrong? Or is it if you swap a early fuel gauge in a late model cluster, it will read wrong?



I'm wondering if my problem is my actual cluster and not just the fuel gauge. Although I got another cluster out of apparently another 318is but I can't confirm it.




I feel like I've honestly looked a every component in the system that would cause this and nothing has fixed it.

[Jean]

I've done the following and can tell you this much:

late model cluster in early car = fuel gauge will read HIGH, fuel low light will read correctly.

late model cluster in early car with early fuel gauge = fuel gauge will read correctly and fuel low level light will read correctly as well.

318i(s) clusters do not have the green plug at the back of the speedo/odo.

[91 318is]

I've done the following and can tell you this much:

late model cluster in early car = fuel gauge will read HIGH, fuel low light will read correctly.

late model cluster in early car with early fuel gauge = fuel gauge will read correctly and fuel low level light will read correctly as well.

318i(s) clusters do not have the green plug at the back of the speedo/odo.

Hmm, but I wonder about early clusters in late cars?

What's this green plug? Do I need to take the cluster apart and look or are we talking about the plugs on the back of the cluster itself?

I have a buddy with a 318is that I may see if he'll let me try his cluster and see what happens.

[Jean]

At the back of the cluster... 325 cars have it but the m42 cars do not. Do you know FOR SURE where the cluster came from, it's never been tampered with, correct fuel gauge? I have a late model 325i and 318i clusters in the garage I can get the part numbers from for you if you want. The circuit for the fuel gauge is REALLY simple, you can look in th ETM for yourself. The gauge is connected directly to the sender(s).

[91 318is]

At the back of the cluster... 325 cars have it but the m42 cars do not. Do you know FOR SURE where the cluster came from, it's never been tampered with, correct fuel gauge? I have a late model 325i and 318i clusters in the garage I can get the part numbers from for you if you want. The circuit for the fuel gauge is REALLY simple, you can look in th ETM for yourself. The gauge is connected directly to the sender(s).

I got the cluster from Matt (MR 325) and he said he's positive it came out of a M42 car. I took it apart to check the PN on the gauge and it's the same part # realoem calls for.

I'm just wondering if the actual circuit on the cluster itself is differnet between early and late models. That's why I was wondering about a cluster part # to see what year the test cluster I bought is from to make sure.


I know the circuit is VERY simple, that's what has me stumped. I've changed everything in the system, only thing that is used is cluster, which is why I'm second guessing it. There's also a guy at work that has a 89 M42 cluster that he said I could try out, I may do that too.


Something makes me keep going back to the cluster, I swear it has something to do with it.

[Jean]

Cluster should not make a difference according to the schematics in ETM. Try another cluster if it's 100% knowing working good cluster, as it would be the next easiest thing to do. Report back how the gauge works then.

I attached 325i cluster circuit and late model 318i to compare.

[91 318is]

Cluster should not make a difference according to the schematics in ETM. Try another cluster if it's 100% knowing working good cluster, as it would be the next easiest thing to do. Report back how the gauge works then.

I attached 325i cluster circuit and late model 318i to compare.

I'm gonna take the cluster out the 89 today and try it when I get home, I'll let you know what happens.


I'm confused about the 2 circuits you posted, they're the same except the circles and one sender X'd out.

I'm pretty tired this morning so I may missing something, lol.

[91 318is]

MADE PROGRESS!

I took the cluster out of my buddies 89 M42 and plugged it in and the gauge is reading different then my other one's. The gauge was reading below 1/2. I swapped my coding plug in his cluster to see if that's the problem and it still worked.

So obviously it's cluster related. Now I gotta find out why my cluster is causing the problem. I know it's not the gauge, it's got a new SI board too.

[91 318is]

Went back to confirm it's the cluster by plugging my original one back up one for time and reads almost full.

Here's a few things I noticed if it makes a difference.

My original cluster is a VDO, the other 2 are motometer's.

Here's what the motometer sticker on the backside of the cluster says on the cluster I bought for troubleshooting:

616 394 4353

1 394 326

Index 20

12V


Here's what the sticker says on my buddies 89 that works in my car:

616 044 4351

1 394 317

Index 20

12V



Does any of this stuff make sense to anyone? Are these actual part #'s or just production numbers?

I really want to figure out the EXACT cause of the problem, not just say it's cluster related.

[91 318is]

Here's another thing I found. I pulled my buddies 89 cluster apart to look at the fuel gauge part # and it's different then the other 2 gagues I tried.


This one reads:

9 3030 150 80

1 374 822


The other 2 gauges have this same part #1 381 366


So it looks like I have the wrong part number fuel gauge? According to realoem, I'm suppose to have # 1 381 366