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Discussion Starter · #1 ·
Ok so I am trying to get the '92 road worthy & the VSS / V.S.S. / vehicle speed sensor seems to be the last thing holding me back.

The bad part:

(note the housing from the transfer-case with plastic gear is still attached)

I took the whole assembly out to ensure I wasn't just dealing with a chewed gear. NOPE, not the gear. I did test the sensor itself by spinning it with a power drill with the engine running & a spotter in the drivers seat hoping the speedo would move, it didn't.

Did you know the VSS is a ~$350.00 part?! :shock:

I hit up the local junkyards inventory pages online, no '92 Troopers. Well lets see if there are any other models that used the same exact part #.... NOPE! Friggin' really?! None? Not that I was able to find, not even other makers used this hunk of junk. Ok lets focus back on Isuzu, why don't the other Utility Vehicles use this sensor, what do they use?

Good part:
'93+ sensor with harness end from donor vehicle

(BTW this little beauty is only ~$225)

Wait a minute, that looks pretty darn close to the same... Upon close inspection you can see the same overall sensor size/shape, even the same housing & gear. But wait! there are three differences! 1. The '92 VSS has about an 18" pig-tail plug, the '93+ has the plug built into the sensor. 2. The '92 sensor is in a metal shell, the '93+ is in a plastic shell. 3. The three wires are the same colors, but in a different order.

A few models have a 3rd sensor that is very different in appearance, we will skip those.

Since my '92 sensor is bad anyway it doesn't need its pig-tail anymore. I am going to splice the pig-tail from the '92 sensor onto the harness end from the '93+ sensor. Unless there are some insane internal differences this should work well.

I'll post a pic of the finished product later.

~psguardian
 

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Discussion Starter · #2 ·
Ok So I've gotten the harness ends mated & the sensor installed, still no good. I'm thinking of a few possible issues:
A. Broken/loose wire in the vehicle harness between sensor & Speedometer/Odometer unit
B. Broken Speedometer/Odometer unit
C. I wired it wrong
D. I replaced a bad sensor with another bad sensor

A = Entirely possible, I didn't (but should have) check this before deciding that the VSS was bad lol.
B = Also possible, but about as involved to check as the wire that goes to it.
C = I don't think so, but its possible.
D = That would just suck, fortunately I grabbed 3 of them when I was at the yard.

My '92 is coded like this :
Black = GROUND
Red = HOT when key is in the ON or START position
White = Signal output to Speedometer (4 pulses per rotation)

The Donor Plugs have : Black, Red(w/white stripe), Yellow... I guessed as follows
Black = GROUND
Red = HOT when key is in the ON or START position
Yellow = Signal output to Speedometer (4 pulses per rotation)

I need help confirming that I wired the harnesses together correctly. Would someone please check their '93-'95 Trooper FSM electrical trouble shooting book for the VSS wire color coding & check my guess please? (Mine was on page 33)

TIA,
~psguardian
 

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Discussion Starter · #3 ·
Bump for the day crew.

Also, just found a great test procedure for both the VSS in the trans & the VSS in the speedo housing (basically the motor for the needle). VSS Test.

I think this diagram means I wired it right, but would still like confirmation from someones FSM ('93-95 trooper or rodeo or amigo, same sensor)

~psguardian
 

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Discussion Starter · #4 ·
Went to Radio Shack & picked up some 2.2k Ohm resistors (5pk=$1.19) & hooked up the cut up old sensor to the battery as the link shows... It works just fine! :cussing:
Sooo..... I cut up a perfectly good VSS :banghead: :banghead: :banghead:

That means its the wiring or the Speedo/Odo unit. Guess the dash is coming apart anyway, at-least the instrument panel.

~psguardian
 

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Discussion Starter · #6 ·
Well with the instrument cluster out I followed the test procedure for the speedometer layed out in the link...

I'm confused because my FSM says 'solidstate, do not test resistance' but the link does exactly that. By the links directions either my cluster housing is boned, or the speedo itself is. Unless the test isn't valid... I'm planning on getting a dash cluster to swap in, we'll see.

~psguardian
 

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Discussion Starter · #8 ·
YJ-4BT said:
Any updates?
Well.... I have tried a second cluster & two diff VSS units, still no speed reading. Bradzuzu gave me a 3rd dash cluster that is known to have a good speedometer w/bad odometer. I have yet to swap it in due to life laughing at me & throwing my Todo list to the wind. & just incase I didn't post it above.... My orig VSS tested good, so I never needed to pull it i'm the first place.

~psguardian
 

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The VSS has power, ground and signal. The sensor works by grounding the signal wire. So the VSS may be good but like you say is the wiring is bad you get no signal. I would not worry about cutting up your stock one. The later model ones are cheaper and more plentiful. You original one was a one or two year only deal.

Number one is to check the fuse and make sure you have 12V ign power at the plug. Next check continuity at the plug to any part of the chassis. Next back probe the signal wire and ground wire with your meter and turn the key on and rotate the sensor. You should get an intermittent continuity between the signal wire and ground.

Do the same at the instrument panel with the signal wire.
 

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Discussion Starter · #10 ·
What all runs off the ign fuse? The sensors i'm using are confirmed good (they give signal pulse as described in one of my earlier posts), the neg wire at sensor is good, the pos wire asst sensor is 'key-ON only' & good, the signal wire from sensor to cluster shows good continuity.

The only variables left to test are the cluster, because I have not found one that tests 100% good. Also the wire from cluster -to- ECU, & the ECU itself.

Anyone know what pin on the ECU plug is VSS signal in?

~psguardian
 

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hi there,
i'm in new Zealand, have spent the last 2 weeks trying to sort out the exact same problem with my 92 bighorn,(I think you call them troopers) noticed your thread after surfing the net for ideas & was wondering if & how you got the speedo going on your trooper, any help would be appreciated,cheers
 

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Discussion Starter · #14 ·
I had to check mine bit by bit, but in the end it still didn't work.

I think I had multiple failures within the system. My vss wasn't producing a pulse signal, so I put in another one (which did produce the pulse signal). It still didn't work, I had also swapped out the dash cluster with one that was in better shape & known to be working. Still nothing. I ran a jumper wire from the sensor directly to the cluster (bypassing all potential breakage points in the wiring harness), still nothing.

The only things I didn't check before giving up were the wires between the cluster & the brain, and the brain itself. Links in this thread should take you to testing procedures for the cluster gauge & the vss itself. You'll need a digital multi meter & voltage meter.

~psguardian
 

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kool thank you, yes I have read the entire link over the past week,(VERY HELPFUL) thanks, I just couldn't see if you had fixed the problem,
I just replaced the trans in mine with a later model trans & the plugs were cut off the end of the wireing on the trans so your thread has been good to work out the wireing on this part of it,
been a pain in the backside because theres 15 wires & the colour coding on the wires are different from the new trans to my wagons wiring loom
I am having trouble finding the metal VSS over here, plenty of the newer plastic ones though, there are 92's over here with the plastic sender on them so there must be a way for it to work
cheers
 

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Discussion Starter · #16 ·
'92 was the only year with the metal ones. The plastic ones are fine, you just have to match up the removable plastic gear (tooth count varies, which changes Speedo readings), and the 12v+ / 12v- / signal wires.

The guts of the sensor (metal or plastic) are the same. Since you've already had to splice the harness ends there is no reason not to use the plastic ones that are readily avail.

~psguardian
 

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Hey Guys, I have a 1992 Trooper S with the same problem. I had a speedometer that intermitently worked. I thought it was the speed sensor so I converted my old one so it would run the new style. now it doesnt work at all. Could it possibly be the brain itself? ive just done everything I can do and I cant give up because it needs to be road worthy.. having the odo not spin is bad.
 

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hi mate yes they seem to be a bit of a problem, I replaced the speed sensor twice, the ecu, the auto control unit, all the wiring with a new wiring loom ,had all the dash out to make sure the were no hidden fuses anywhere behind there & most of my 2 months off on holiday working on mine, still couldn't get it to work, I had the same problem, needed it working for a warrant of fitness, but in the end I just gave up & went & bought another bighorn, the 92 is just sitting in the drive now, was an expensive waste of time for me, spent just short of 2 grand on parts for it including the trans, if you want my advice i'd say take it to an auto electrician at least you know its his job to get it working & he's got the tools & know how to get it working,
cheers & good luck
 

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Unfortunately there arent many places that just deal in auto electrical, and since isuzu is no longer a brand sold here in the states we dont have a dealer either. But I will look into that as an option. The sendor I pulled was off of a rodeo and who knows if it was any good. Just ver frustrating.
 

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So I was reviewing these posts...now several years old. Why? Because I am going through the very same problems! The difference is that I have a success story on my hands and wanted to share it with my fellow Isuzu Trooper brethren.

I was getting the code 24 indicating bad VSS. Spent $192 to get a new since mine appeared to be totally out of commission based on the bench test posted elsewhere in this string of inputs. Only while waiting for the part to my wife decided to hit eBay for a used '92 Trooper S speedometer...which she found(!). Installed the vss alone, test drove it and as luck would have it, no joy. Left it in place and added the new (used) speedo and...SUCCESS!

I hope each of you...especially psguardian...we're able to resolve your own vss problems.

Btw... my 92 Trooper was a garage queen for 3 years, but a new alternator, new head gaskets, new Gabriel Ultra shocks, new vss, used speedometer, and a new battery, I'm almost back to fully stock condition. All I really need is new tires...I'm open to recommendations ...and a replacement radio. I'm really diggin' my Trooper! Thanks to all for the very informative posts! rrb
 
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