No Tach

[McGyver]

The biggest difference is earl/late clusters. Components can't be swapped between them, and I don't believe you can but an early cluster in a late car and vis-versa. I believe you can swap motometer into VDO clusters and vis-versa.

[Gtfour]

tachs are the SAME between 4 and 6 cyl cars. There's no 4cyl and 6cyl tach. The coding plug is different. He needs coding plug 1394321 for the 4cyl 7k cluster.

If the entire cluster was swapped with a 6cyl cluster, the coding plug is likely incorrect for his car.

The 318iS also has a single sender, smaller fuel tank, so the M20 late model 6cyl cluster fuel gauge won't read right if installed in a 318iS chassis.

Late model 6cyl cluster = different coding plug and fuel gauge than Late model m42 cluster , otherwise the same.

That means the same SI board, tach, speedo, casing, coolant temp gauge, main board, etc.

Thanks a lot!

Everything else ‘’work’’ in my cluster, except mileage gears needs to be replaced, coolant temperature gauge works but heater valve needs to be replace, right side lights won’t work, …

I haven’t start working on this car yet but it needs a complete overhaul and still not sure which route I want to go with the engine…

[82eye]

It’s impossible to say what cluster they have without more info

the coding plug is the same physical size.

different in the coding part, same in the plug part

yeah i just saw the difference is internal but the plugs are physically identical. i didn't expect a processor in the plug but it makes sense. cheaper for a company to change a plug between cars than build a whole different tach.

[AWDBOB]

so he's got a whole cluster from the 6 then ? i always thought the plugs were different between the 6 and 4 tach and would not swap. how does changing a plug fix anything if they are the same ?

It’s impossible to say what cluster they have without more info

the coding plug is the same physical size.

different in the coding part, same in the plug part

[82eye]

ok answered my own question .. the plugs are physically the same but there is a small processor and pcb board inside which changes between the different cars and clusters.

[82eye]

Si board is the same between the two, as is the cluster housing, so the coding plugs are plug n' play

so he's got a whole cluster from the 6 then ? i always thought the plugs were different between the 6 and 4 tach and would not swap. how does changing a plug fix anything if they are the same ?

[AWDBOB]

are the coding plugs swappable between the two or are they physically different? if the plugs are different, not sure how it's able to plug it in or get any tach signal.

the tach does work off a pulse. i've seen this happen on cars other than bmw between a 6 and 4 cyl.

Si board is the same between the two, as is the cluster housing, so the coding plugs are plug n' play

[82eye]

tachs are the SAME between 4 and 6 cyl cars. There's no 4cyl and 6cyl tach. The coding plug is different. He needs coding plug 1394321 for the 4cyl 7k cluster.

If the entire cluster was swapped with a 6cyl cluster, the coding plug is likely incorrect for his car.

The 318iS also has a single sender, smaller fuel tank, so the M20 late model 6cyl cluster fuel gauge won't read right if installed in a 318iS chassis.

Late model 6cyl cluster = different coding plug and fuel gauge than Late model m42 cluster , otherwise the same.

That means the same SI board, tach, speedo, casing, coolant temp gauge, main board, etc.

are the coding plugs swappable between the two or are they physically different? if the plugs are different, not sure how it's able to plug it in or get any tach signal.

the tach does work off a pulse. i've seen this happen on cars other than bmw between a 6 and 4 cyl.

[AWDBOB]

Yes but if I have the 318is original cluster, what is the other part that isn’t compatible with it?

sounds like the tach has been replaced with a 6 cyl tach.

edit : the tachs are electronic. they read off pulses when the cylinders fire. a 6 cyl tach registers one revolution every 6 pulses. if you have a four banger it will read slower as it only gets 6 pulses every revolution and a half on a 4 cyl. it'll register a third or so slower.

tachs are the SAME between 4 and 6 cyl cars. There's no 4cyl and 6cyl tach. The coding plug is different. He needs coding plug 1394321 for the 4cyl 7k cluster.

If the entire cluster was swapped with a 6cyl cluster, the coding plug is likely incorrect for his car.

The 318iS also has a single sender, smaller fuel tank, so the M20 late model 6cyl cluster fuel gauge won't read right if installed in a 318iS chassis.

Late model 6cyl cluster = different coding plug and fuel gauge than Late model m42 cluster , otherwise the same.

That means the same SI board, tach, speedo, casing, coolant temp gauge, main board, etc.

[82eye]

Yes but if I have the 318is original cluster, what is the other part that isn’t compatible with it?

sounds like the tach has been replaced with a 6 cyl tach.

edit : the tachs are electronic. they read off pulses when the cylinders fire. a 6 cyl tach registers one revolution every 6 pulses. if you have a four banger it will read slower as it only gets 6 pulses every revolution and a half on a 4 cyl. it'll register a third or so slower.

[Gtfour]

sounds like what you suspect.

Yes but if I have the 318is original cluster, what is the other part that isn’t compatible with it?

[82eye]

I also have a tach question. I have a 318is. The tach is working but the rpm doesn’t match the actual engine rpm. It’s going to like half of the real rpm. Could it be mismatch parts from a 325 or early model? I bought it from a guy who had couples of E30 and bunch of spare parts and I have parts frim couple different cars on it…

sounds like what you suspect.

[Gtfour]

I also have a tach question. I have a 318is. The tach is working but the rpm doesn’t match the actual engine rpm. It’s going to like half of the real rpm. Could it be mismatch parts from a 325 or early model? I bought it from a guy who had couples of E30 and bunch of spare parts and I have parts frim couple different cars on it…

[82eye]

I have a Tach! It turns out the Fuse 21 wiring was NFG.

AWDBOB for the win!

nice work. thanks for posting the fix. wish more folk would do that.

[twright]

I have a Tach! It turns out the Fuse 21 wiring was NFG.

AWDBOB for the win!