last wire... from back of tach?

[MattM]

ok, everyone says run a wire directly from the back of the tach(green connector) to pin 14. do i take the existing one and route it to 14, or create a totally new one(so there are 2 going into the back)?

[tonytony]

? be more specific, all my guages work and i never did anything with the tach wire

[rThor432]

OP, I think you are talking about the vehicle speed sensor wiring. That green wire you mentioned should be behind the speedometer and it is a speed sensor pickup for the cruise control.

A lot of aftermarket chips negate the need for that wire. I know for one that the Conforti software ignores that input and I believe that the TRM chip does as well.

[mongule]

What year is your car?

[MattM]

sorry, its an 84 325e, PFL car. it does have cruise control too...

yes, i think its the speed sensor that i am refering too..

[mongule]

Ok, why do you say you already have a wire going to the back.

[MattM]

becuase i am wondering if that wire is needed anymore with the M50, so i could cut it and hook it into pin 14 of the x20. or do i need to add a totally new wire that goes from the green connector to the x20 plug?

if its the cruise control wire, then i am assuming i need to leave it and add another wire?

[m_dudey]

I'm going to bring this tread back up.

So I finally got my cruise control throttle cable hooked up properly and went for a drive to test it out. got up to freeway speeds and set the cruise control.... nothing!

came back and did some searching on R3V and people say to make sure the wire from the back of the speedometer is connected. Mine is connected on the back of the speedometer. Also, mine is an 89 model, which means the DME gets the speed sensor signal via c101 pin14 to x20 pin 14 from the instrument cluster.

In the following post, Jason89i suggests a way to test if the speed sensor is hooked up correctly.

http://r3vlimited.com/board/showpost.php?p=1676063&postcount=3

I tried it and while I'm coasting with clutch in, my revs seem to be at idle instead of a raised rev. So it seems that my speedsensor is not working properly? Which is why my cruise control isn't working either?

Then I run across this thread where rThor432 says

A lot of aftermarket chips negate the need for that wire. I know for one that the Conforti software ignores that input and I believe that the TRM chip does as well.

So I have a TRM chip, does this mean that the DME is ignoring the speed sensor signal and hence I don't get the raised rev while coasting and why my cruise control does not work?

[BeirBrennerE30]

ummm no.

VSS does not go through c101 on any e30. The green connector on the back of the speedo is for the cruise control. You need that wire hooked up to the proper plug for the cruise to work since it needs the VSS for feedback.

Also you need to add another wire to that plug and run it to the DME. The ECU needs The speed signal for the top speed limiter and rumor has it with out this signal it limits rev limit. Depending if you have a chip your results may vary.

[matt]

I'm going to bring this tread back up.

So I finally got my cruise control throttle cable hooked up properly and went for a drive to test it out. got up to freeway speeds and set the cruise control.... nothing!

came back and did some searching on R3V and people say to make sure the wire from the back of the speedometer is connected. Mine is connected on the back of the speedometer. Also, mine is an 89 model, which means the DME gets the speed sensor signal via c101 pin14 to x20 pin 14 from the instrument cluster.

In the following post, Jason89i suggests a way to test if the speed sensor is hooked up correctly.

http://r3vlimited.com/board/showpost.php?p=1676063&postcount=3

I tried it and while I'm coasting with clutch in, my revs seem to be at idle instead of a raised rev. So it seems that my speedsensor is not working properly? Which is why my cruise control isn't working either?

Then I run across this thread where rThor432 says



So I have a TRM chip, does this mean that the DME is ignoring the speed sensor signal and hence I don't get the raised rev while coasting and why my cruise control does not work?

rThor is not correct, TRM chips do require the speed sensor to be connected.

Your cruise control working or not working is not related to your ECU whatsoever. If you don't have a code for the speed sensor stored in the DME than the signal is good from the diff to the cluster and from the cluster to the DME. So the problem may be elsewhere within the cruise control system (clutch switch or neutral switch or brake switch or...)

ummm no.

VSS does not go through c101 on any e30. The green connector on the back of the speedo is for the cruise control. You need that wire hooked up to the proper plug for the cruise to work since it needs the VSS for feedback.

Also you need to add another wire to that plug and run it to the DME. The ECU needs The speed signal for the top speed limiter and rumor has it with out this signal it limits rev limit. Depending if you have a chip your results may vary.

VSS certainly does go through the C101 on some models.

[MattM]

wow, this thread is back.. i never did get my cruise control working. the servo does not respond to any input, i even just plugged it in with the servo sitting in my lap and went for a drive, no matter how i pull/ push on it or what i do with the control lever nothing happens... so i figure my servo is shot, i dont have the desire to replace it at this time.

I do however get the raised idle when moving, it bumps up to about 1100rpm, so i know the VSS is working

[m_dudey]

the raised idle while moving, is that with the clutch disengaged? or with clutch engaged but in neutral gear?

[Jean]

rThor is not correct, TRM chips do require the speed sensor to be connected.

Your cruise control working or not working is not related to your ECU whatsoever. If you don't have a code for the speed sensor stored in the DME than the signal is good from the diff to the cluster and from the cluster to the DME. So the problem may be elsewhere within the cruise control system (clutch switch or neutral switch or brake switch or...)


VSS certainly does go through the C101 on some models.

Late model 318i(s) correct? I've never seen 16v cars even use a green plug at the back of the cluster.

[MattM]

is that with the clutch disengaged? or with clutch engaged but in neutral gear?

it doesnt matter, there is nothing on the transmission that relays weather or not the clutch is enguaged to the DME. SO that wont affect it at all.

The VSS is on the diff in the rear. so anytime the rear wheels turn its picking it up.

[BeirBrennerE30]

VSS certainly does go through the C101 on some models.

What models? Not any with an s14, m20 or m10.