vss and speedometer problem - Honda Prelude Forum

amnidab · 07-31-2009, 11:22 AM

having problem with my 95 speedometer not working, have read most of the postings dealing with the vss unit and the speedometer gauge.
would someone tell me how to determine if the vss is causing my speedometer to read out the wrong speeds, as opposed to the gauge itself causing the problem?
tks

yohan420 · 07-31-2009, 02:04 PM

multimeter.

have you checked the Helms manual for troubleshooting steps? thats the first place i'd look.

amnidab · 07-31-2009, 08:52 PM

any one want to disclose a trouble shooting proceedure?

indylude18 · 07-31-2009, 09:00 PM

Here you go, just download the helm's for free here:

Free downloadable Honda and Acura Factory Service HELMS Manuals

Happy Troubleshooting

amnidab · 07-31-2009, 10:17 PM

thank you for the helms link, will take a look.

SNsLude · 08-01-2009, 01:32 AM

Yohan provided you with the answer. Looking at the helms will just tell you to use a multimeter to check the VSS out, just like he said.

darkstar67 · 08-01-2009, 01:39 AM

Are you still running stock wheels? How bad off is the speedo? Does the speedo bounce when you take off?

amnidab · 08-02-2009, 01:18 PM

wheels are stock, speedometer reads 20-30mph when barely moving and it stops around 60 mph when going faster.

amnidab · 08-02-2009, 01:21 PM

i read the helms on the vss, i will check the wires to the vss with my voltmeter, but helms proceedure stops short to tell me my original post questions. i found nothing in the helms manual about testing my speedometer.

darkstar67 · 08-02-2009, 11:46 PM

Dude you owe me big time for this ****... uhggg.

-Road test necessary. with manual transmission in 2nd gear(a/t 2 position) accelerate to 4000 rpm, then decelerate to 1500 rpm with throttle fully closed.

-Is the MIL on and does it indicate code 17?
-If no, then itermittant failure, system is ok at this time. check for poor conections or loose wires at c433 (located at right shock tower), c115 (VSS) and ecm.
-If yes, Then continue with testing below.

-Block rear wheels and set parking brake. Jack up the front of the car and supprort with safety stands.

-Turn the ignition OFF.

-Conect the test harness between the ECM and connectors (see page 11-45)

-turn the ignition switch ON

-Block the right front wheel and slowly rotate left front wheel and measure voltage between B10 (+)and a26 (-) teminal.

-------------------------------------------------
0000000000000 l 00000000 l 000000 l 00000000000
000000000000A l 0000B000 l 000000 l 00000000000
--------------l-------l---------------------------
a26 is the last one on the bottem, first cluster of pins. A26 is your (-)
B10 is the fifth one on the bottom, second cluster of pins. B10 is your (pos)
They are marked so this is idiot proof.

-Does voltage pulse 0V and 12V on H22a1 engine? 0V-5V on H23 and F22 engine?
-If yes, substitute a known-good ecm and recheck. If symptom goes away, replace original ecm.
-If no, turn the ignition switch off.

-Disconnect the B connector from the ECM only, not the main wire harness.

-Turn the ignion switch ON.

-Block the right wheel and slowly rotate the left front wheel and measure voltage between B10 and A26 again.

-Does voltage pulse again?
-If no, Repair short in ORN (orange?) wire between ECM B10 and vss, transmission control module, speedometer, 4ws control unit, or cruise control unit.
-If no, repair open in ORN wire between ECM B10 and vss.
-If yes, substitute a known good ecu and recheck.

Ive got another one to check the vss system to see if its the speedo or not, If you want me to post it. this didnt take me near as long as I thought it would lol.

darkstar67 · 08-02-2009, 11:57 PM

Ive been reading more on this in my manual and it really does point to having a bad ecu or a bad speedo. I really dont think its your VSS because your symptoms arent listed anywhere for a vss. Do you live anywhere near cookeville tn? If you do we can just swap parts to see what is bad because testing all of this stuff can take a while, whereas changing a vss is one clip and one bolt.

amnidab · 08-04-2009, 04:11 PM

thank you for your proceedure, but i dont have another ecm.
i ran the 4000rpm test and decellerated to 1500rpm. mil light didn't come on, so it looks ok.

can you send vss/speedo proceedure? I live in wichita, ks.
i can not find a test to isolate the speedo validation?
tks

amnidab · 08-04-2009, 04:16 PM

after studying this, i agree with you, i don't believe this is the vss due to the lack of symptions. the car runs and idols fine, although it does shift gears a little hard but smooths out when engine warms up. I would like to take out the speedometer but can not tell how to determine if it is good or bad. also
ebay sells new vss units for $18 and used speedo's for $60. I would rather send one of you guys a 6 pack for the help rather than buy a part off ebay i don't need.