The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Morrison Fabrications
Please Support ExtremePSI

2G Quick question regarding VSS

tay97gst

10+ Year Contributor
476
32
Dec 20, 2011
Plaistow, New_Hampshire
Hey guys,
I just got my car on the road for the first time since doing a few things to it over the winter. Everything seems to be going well except for the fact that my speedometer isn't working. I know that it's not a problem with the cluster because ECMlink isn't logging speed either so it must be something with the VSS itself.
Now here's the thing, over the winter I did a fusebox relocation and deleted the ABS unit and wiring.
My question is, does the VSS require any part of the ABS system to work correctly? Or does it work in conjunction with any other system for that matter?
I'm just trying to figure it if it's something to do with the wiring that I pulled out or if it's just a coincidence and now the VSS went bad. Which I suppose would be possible since I pulled the engine and trans so they were moved around a bit.
Thanks for any help!
 

2gmitsueclipse

DSM Wiseman
2,380
742
Jul 13, 2005
Auburn Hills, Michigan
According to the FSM, it is a 3 wire connector. Neither of which are wired into the ABS circuit.

If it helps:

Black/white stripe>Ignition switch
Black>Ground
Yellow>ECU

I would verify that the connector or sensor itself are not damaged, or that the connector just is not on good enough.
 

tay97gst

10+ Year Contributor
476
32
Dec 20, 2011
Plaistow, New_Hampshire
According to the FSM, it is a 3 wire connector. Neither of which are wired into the ABS circuit.

If it helps:

Black/white stripe>Ignition switch
Black>Ground
Yellow>ECU

I would verify that the connector or sensor itself are not damaged, or that the connector just is not on good enough.

Alright man, thanks for the info. I wouldn't have guessed it was tied into something else but I wasn't sure. I'll pull back some of the sleeving and inspect the connector to check for damage. Otherwise I guess I'll assume the wiring is ok and try and replace the VSS itself. I just found it very coincidental.
 

tay97gst

10+ Year Contributor
476
32
Dec 20, 2011
Plaistow, New_Hampshire
Also make sure the connector clip is on properly or the connector can get loose and loose contact: http://www.dsmtuners.com/attachments/speed-sensor-connector-jpg.124250/

Just went out and used a multimeter on the connector to verify the connector and wiring are in tact. Ignition wire is receiving 12v and the ground wire checked out. Since I know the wiring is ok I'll probably just bite the bullet and order a new VSS. Maybe it got hit while the trans was out or something :idontknow:
 

tay97gst

10+ Year Contributor
476
32
Dec 20, 2011
Plaistow, New_Hampshire
You can check the VSS by looking for pulses on the data link (OBD2) connector pin 14 (http://www.obdii.com/connector.html). Jack up front of car, block one wheel from turning, turn key to on (engine not running), and manually turn other wheel. Should see pulses. Or you can drive the car and monitor pin 14.

I actually removed the speed sensor but left the connector on, and connected to ecmlink to monitor the "speed". As I spun the gear at the bottom there was zero change, it stayed at 0mph the whole time. Considering I've confirmed that the connector's wires are active and that even the ecu isn't receiving any signal should that sufficiently confirm that the sensor is dead?
 

tay97gst

10+ Year Contributor
476
32
Dec 20, 2011
Plaistow, New_Hampshire
Alright so I got the new VSS in and tried testing it like I did the other one but got the same results. I decided to test the connector again using a more sure ground for my multimeter and got these results.
With key in start position testing multimeter at connector:
Black/white stripe>Ignition switch - 12v
Black>Ground -12v
Yellow>ECU - 9v

So I'm not sure where to go from here. I'm not sure why the ground wire is receiving 12 volts, does that make any sense whatsoever?

Edit: Just a thought. I know it's assumed that removing the ABS shouldn't have to do with this... but I also put on JDM knuckles and didn't get wheel speed sensors because I thought they were only there for the ABS system, am I wrong with that assumption?

Edit #2: Also, I found this diagram trying to figure out the circuit for the VSS. Is this showing that part of the VSS signal goes though the AC and cruise system or am I reading it wrong? I'm just concerned because I removed the AC and cruise from the fuse box when I did the relocation.
 
Last edited:

tay97gst

10+ Year Contributor
476
32
Dec 20, 2011
Plaistow, New_Hampshire
Unfortunately I'm back with more questions than answers and I really could use some help. I did some more digging but am not sure what to make of the results.
Using this diagram from above I did some testing at connector C-22 and pinout 14 on the OBD-2 port.

Here's what I found:
With the VSS unplugged from the connector:
C-22 VSS sensor side - 4.62V (Note that this connector is unplugged to take the reading)
C-22 Interior Harness side - 9v
Pin 14 on OBD2 - 9v
With C-22 connected:
Yellow wire on VSS connector - 9v (With C-22 unconnected im pretty sure this read 4.62v)
Black wire on VSS connector - only wire with continuity but also reads 12v?
Black/White wire on VSS connector - 12v

VSS plugged in to connector:
C-22 VSS sensor side - 11v (Note that this connector is unplugged to take the reading)
C-22 Interior Harness side - 9v
Pin 14 on OBD2 - 11v
With the VSS plugged in and C-22 connected there is no voltage change in pin 14 of the OBD-2 while spinning the gear, it stays constant at 11v.

That's all of the information I collected, and I'm honestly not sure where to go from here. If this makes sense to anyone please let me know what I can test next.
 

waltah

10+ Year Contributor
369
154
Mar 2, 2011
fairfield, Virginia
You have a turbo or a non--turbo with M/T, right? The non-turbo A/T cars have a different setup entirely.

The circuit diagram shows the VSS as a transistor switched by an input that might be magnetic. The transistor output appears to be pulled up by a resistor in the PCM/ECM so you won't get a signal without having everything connected.

However, per the manual you can fake the PCM/ECM pull-up if you connect a 3k to 10k resistor from pin 1 to pin 3 with pin 1 to the battery + and pin 2 grounded. You probably don't have that resistor handy but a cheap multimeter is often 1k ohms/volt of the selected full scale reading and no harm in trying. Hook up 1 to bat+ and 2 to ground then set multimeter to 5v or whatever's the next higher scale, connect the red lead to the bat + and black to pin 3, then turn the shaft. The needle should jump back and forth as you turn. 1 turn = 4 pulses.

This checks the VSS sensor itself and if you do the test at the PCM/ECM end of the connection to pin 3 it also checks the harness.

This test might not work if you have a better quality multimeter -- say 20k ohms/volt. Look for small print on the face of the meter -- it'll probably tell you. Definitely won't work with a digital meter --- you need one with a real moving needle.

The only other possibility listed in the manual is the PCM/ECM -- I'd try to borrow one to substitute for a test.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned VR Speed Factory

Latest posts

Build Thread Updates

Latest Classifieds

Top