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Username Post: speed doesn't work        (Topic#354079)
jetboat36 
Poster
Posts: 16

Reg: 11-21-18
11-26-18 09:34 PM - Post#2752478    

so i pull the speed sensor of the t case and test it out with a voltmeter and a drill the sensor work good. so why the speed still doesn't work ?



 
tcndeb 
Senior Member
Posts: 400

Loc: Texas
Reg: 04-18-04
11-27-18 07:20 AM - Post#2752509    
    In response to jetboat36

on what?


'92 Full Size Blazer


 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
11-27-18 09:23 AM - Post#2752527    
    In response to jetboat36

You must be talking about a square body. All GMT400s use electronic speed sensors and you can't test them with a drill.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
jetboat36 
Poster
Posts: 16

Reg: 11-21-18
11-27-18 12:20 PM - Post#2752546    
    In response to bowtie44s

on a 1998 k2500 is the one with 2 wire the tip is a magnet the one in the tcase. and yes you can test it out with a drill i did and i can see on the voltmeter the sensor work .....



 
jetboat36 
Poster
Posts: 16

Reg: 11-21-18
11-27-18 02:50 PM - Post#2752561    
    In response to jetboat36

anyone got the wiring diagram ?



 
tcndeb 
Senior Member
Posts: 400

Loc: Texas
Reg: 04-18-04
11-27-18 03:11 PM - Post#2752563    
    In response to jetboat36

don't have a schematic with me but that should have a vssb in the circuit after the sensor.

'92 Full Size Blazer


 
454cid 
Valued Contributor
Posts: 3026

Age: 45
Loc: West Michigan
Reg: 02-18-12
11-27-18 03:13 PM - Post#2752564    
    In response to jetboat36

  • jetboat36 Said:
on a 1998 k2500 is the one with 2 wire the tip is a magnet the one in the tcase. and yes you can test it out with a drill i did and i can see on the voltmeter the sensor work .....



What are you turning with a drill? I've never pulled mine, but looking at new ones online, it looks a lot like a crankshaft position sensor.

99 K3500 RCLB


 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
11-27-18 06:32 PM - Post#2752580    
    In response to 454cid

  • 454cid Said:
What are you turning with a drill?



That is the part that has me confused.

I had some speedometer problems a few years ago. Here is the thread on how I tracked it down. Hopefully this helps.
https://www.chevytalk.org/fusionbb/showtopic.php?t...

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
jetboat36 
Poster
Posts: 16

Reg: 11-21-18
11-27-18 10:10 PM - Post#2752606    
    In response to 454cid

is for testing the speed sensor since its a magnet at the tip because the sensor produce is own volt i used a dril and a bit make it turn and put the sensor close to it if the ac volt goes up sensor working and he did it ...



 
454cid 
Valued Contributor
Posts: 3026

Age: 45
Loc: West Michigan
Reg: 02-18-12
11-27-18 11:20 PM - Post#2752613    
    In response to jetboat36

  • jetboat36 Said:
is for testing the speed sensor since its a magnet at the tip because the sensor produce is own volt i used a dril and a bit make it turn and put the sensor close to it if the ac volt goes up sensor working and he did it ...



Interesting, so the drill bit is a makeshift tone ring or reluctor. That still doesn't mean that it's sending a signal that means anything, although, I suppose it's a start.

99 K3500 RCLB


 
jetboat36 
Poster
Posts: 16

Reg: 11-21-18
11-28-18 12:15 PM - Post#2752682    
    In response to 454cid

i know but i know the sensor is good so what next should i check the speed sensor buffer box?



 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
11-28-18 04:47 PM - Post#2752719    
    In response to jetboat36

Did you read the thread I linked you to? It should walk you through it.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
jetboat36 
Poster
Posts: 16

Reg: 11-21-18
11-28-18 07:32 PM - Post#2752737    
    In response to bowtie44s

yes i did how far was the burned wire you found ?



 
454cid 
Valued Contributor
Posts: 3026

Age: 45
Loc: West Michigan
Reg: 02-18-12
11-28-18 08:04 PM - Post#2752739    
    In response to bowtie44s

  • bowtie44s Said:
Did you read the thread I linked you to? It should walk you through it.



I just read it... very interesting. My truck being OBD2, I wonder if I can see what the VSS reads directly.


99 K3500 RCLB


 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
11-29-18 06:51 AM - Post#2752764    
    In response to 454cid

It was about a foot from the vss so I didn't have to go very far. I'm not sure if the computer monitors speed or not. That still wouldn't tell you where it is bad.

If I remember right, the first connection is right by the transfer case. Just make sure you have it good and sturdy before you crawl under it.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
Sabino 
Member
Posts: 42

Reg: 07-16-05
12-02-18 09:02 AM - Post#2753089    
    In response to bowtie44s

I had problem where speedo was occasionally erratic & would rise when reving engine in park. problem was sensor in trans. Even though it was functional, signal level wasn't large enough/quality good enough that the VSS could detect reliably. Replaced it and problems went away.

net is just because there is a signal doesn't mean it's a good enough signal to function. Memory is both wires from sensor go to VSS (on my '93 -don't know about newer models), if so you could unplug sensor & VSS, jump connector at sensor and check continuity @ VSS connector.

Just replacing sensor to eliminate that as variable may be easiest/quickest


65 Belair 350
68 Camaro 327
85 Caprice 5.0L
93 Suburban 5.7L TBI


 
bowtie44s 
Valued Contributor
Posts: 4093
bowtie44s
Age: 35
Loc: wv
Reg: 08-29-12
12-02-18 06:47 PM - Post#2753135    
    In response to Sabino

There is no sensor in the transmission unless you're talking about the VSS on a 2WD. It is in the transfer case on a 4WD.

Jeff

'88 Chevy K3500, aluminum head roller cam 511in³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
Sabino 
Member
Posts: 42

Reg: 07-16-05
12-03-18 07:05 AM - Post#2753164    
    In response to bowtie44s

Yes, my experience is with a 93 2WD. I assumed circuit for detecting speed would be same, just different location for the sensor. Is a 4WD different?, no VSS?

65 Belair 350
68 Camaro 327
85 Caprice 5.0L
93 Suburban 5.7L TBI


 
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