Hooked up My Vehicle Speed Signal, Now a Slow Electrical Drain.

[Lof8]

I didn't have any electrical drain problems prior to connecting a Vehicle Speed Signal to the DME.

I took the wire from the back of the speedo (green in color) and spliced it into my harness adapter where it can send the signal to the DME (pin 14).

Before connecting this wire, my car would go into a limp mode after 10 mins. of driving, so it is indeed necessary.

I can park the car overnight and will still have lots of juice. But, if it sits for 4 or 5 days, theres no juice left.

I had no battery issues before connecting this wire.

Any ideas?

[flyboyx]

should i assume you are obd2? also, assuming this to be the case, my speed signal came from the one of the abs sensors. i think we will probably need a little more information to go on other than "the green wire" as colors change over the years.

[Lof8]

I'm obd1. There is a green wire off the back of the speedometer (only wire there) that ran over to where the m20 engine harness connected to the dme from the factory. I believe it may have been a part of the cruise control system. The S50 harness has no provision to hook up this wire.

Therefore, I rerouted this wire through the firewall on the drivers' side and spliced it in at the harness adapter.

[416stroker]

No speed signal shouldnt cause a limp mode...


Its P14 on the s50 harness. What year is you car the wire should be yellow blue?



You connected it to the plug thats circled correct?

You did something wrong. Do you have an etm?

[Lof8]

No speed signal shouldnt cause a limp mode...


Its P14 on the s50 harness. What year is you car the wire should be yellow blue?



You connected it to the plug thats circled correct?

You did something wrong. Do you have an etm?

The speed signal fixed my limp-home-mode problem.

The wire may actually be yellow/blue, I'm unsure and away from my car. My car is an '87 and the wire did indeed plug in where you show in the picture. (The wire was already plugged in but dangling loose on the other end where I had unplugged it from the m20 harness).

What is an etm?

[416stroker]

What did you connect the cluster to? My cars an 87 I went from the cluster to pin 14 in the m50 harness.

If your cars a late model it could be in the c101 so all you would have had to do is go p14-p14


It still shouldnt have cause you limp mode all it does is rase the Idle when rolling to 1200 and rev limit in first gear.

[Lof8]

Here is the thread with my VSS troubles:

http://r3vlimited.com/board/showthread.php?t=156700

It seems my chassis harness did not have a vehicle speed signal at c101 (late '87 build). So, I connected the wire from the cluster to S50 harness pin 14. This solved my limp mode troubles, 1st gear rev limit etc.

I couldn't be happier with how the car runs now. I'm just trying to solve this slow drain issue.

[Kingb]

I have been trying to figure out how you guys know/figure this stuff out?

[416stroker]

Well the best advice I can give you is to break out a voltmeter and check for current draw when the key is off.

[matt]

It still shouldnt have cause you limp mode all it does is rase the Idle when rolling to 1200 and rev limit in first gear.

It lowers the rev limit in every gear when it doesn't see a speed signal because otherwise you could clip that wire and go max out your car.

[Wh33lhop]

It lowers the rev limit in every gear when it doesn't see a speed signal because otherwise you could clip that wire and go max out your car.

Plus, how's it going to know what gear you're in, especially without knowing how fast you're going?