Trouble getting a VSS signal

[nordic]

I have a 1988 Honda Prelude that currently gets about 33 MPG highway. I just recently attempted installing an MPGuino. I don't have much experience with electrical work so this is a fun project.

I have everything connected and working with the MPGuino except the VSS signal. A couple guides online indicate that the ECU B10 yellow/blue wire is a VSS signal. The MPGuino does not read a signal from this wire.

Something else online suggested using the ECU B16 wire, but the schematics says that is the crankshaft sensor ground. I tried it anyways. I got a signal but it definitely was not the VSS signal.

Since I can't get a VSS signal from the ECU wires I thought I should go direct to the source. I can't find the VSS sensor on the engine though. Here are some pictures of my engine.



My question for the Ecomodder experts, where should I get a VSS signal?

[LittleBlackDuck]

VSS sensor is generally on the gearbox. Google shows it as being on top of the transmission and having a black plastic connector on top of it.

Simon

[California98Civic]

Are you certain there really was a electronic speedo then? The civics were still cable driven until 1992. Maybe the Prelude had more features. Maybe it had another way of reading speed for the ECU but I doubt that.

[nordic]

Originally Posted by California98Civic

Are you certain there really was a electronic speedo then? The civics were still cable driven until 1992. Maybe the Prelude had more features. Maybe it had another way of reading speed for the ECU but I doubt that.

By what I have read it has a mechanical magnetic sensor that sense an electrical signal. I have found posts of other people with 3rd gen preludes installing MPGuino's.

[LittleBlackDuck]

Originally Posted by nordic

By what I have read it has a mechanical magnetic sensor that sense an electrical signal. I have found posts of other people with 3rd gen preludes installing MPGuino's.

That tallies with what I have seen. Two places remain for the fugitive VSS sensor - inside the speedo and on the gearbox where the speedo cable connects.

Have a look at this thread as it shows thew VSS sensor and also the gearbox clearly. In your second photo it should be buried somewhere under the distributor and on the top of the gearbox

Simon

[nordic]

Originally Posted by LittleBlackDuck

That tallies with what I have seen. Two places remain for the fugitive VSS sensor - inside the speedo and on the gearbox where the speedo cable connects.

Have a look at this thread as it shows thew VSS sensor and also the gearbox clearly. In your second photo it should be buried somewhere under the distributor and on the top of the gearbox

Simon

I don't see a link, could you maybe PM it then.

[LittleBlackDuck]

Originally Posted by nordic

I don't see a link, could you maybe PM it then.

OOPS! My bad - did not paste correctly.

1FunRyd's 88-91 Prelude - Auto to 5 speed swap, B20A - H23 Non-VTEC swap - Honda-Tech

Simon

[nordic]

That looks nothing like the VSS I was looking for. My googling gave me a different looking VSS.

[LittleBlackDuck]

Hope that helps

Simon

[California98Civic]

Some 3rd gen Preludes have cable, some have electronic. You can buy replacement cables for third gen Preludes from RockAuto and other major carriers. I'll bet diff trim levels had diff specs... you need to follow the check this guy recommends in this Prelude forum thread:

"To check, just look down at the top/rear edge of your transmission bell housing, near the shift linkage. If you see a box with wires, it's electronic, otherwise you'll see a huge cable. Have a look, it's not hard to differentiate them."
Broken speedo cable...easy to replace? - Honda Prelude Forum - PreludeDriver.com