SPEEDOMETER intermittent

[motorhead327]

Top of this page, just to left of the little bell icon is the little envelope icon. Click that for PM.

Got it thanks.....

 

[Leeztruk]

Sent you a new PM

 

[Leeztruk]

Here's the VSS troubleshooting procedures from the '89 Service manual. See if this info will help in your search

 

[motorhead327]

Here's the VSS troubleshooting procedures from the '89 Service manual. See if this info will help in your search

Thanks Lee, I do have that manual plus the electrical one and component repair...

 

[motorhead327]

After two after market vehicle speed sensors, I am back to the OEM. I got one VSS from O'Reilly which buzzed and whined I took it out and filed down the pickup so it would quit buzzing. My speedo problem persisted, I bought another VSS from NAPA. Took out the O'Reilly one and the two pickups were missing. Put in the NAPA one; it buzzed and whined too. Next day noticed what looked like trans fluid in a parking space I pulled out of. Got home and sure enough it was leaking. It had backed out past the O-ring and I knew for sure I had tapped it against the housing shoulder for a good, square seal. See pics. Furious, I am now running around with the OEM one in. Speedo still does as before; intermittent function, but no leaking, no buzzing. The OEM one has "dished out" pickups. See pics.
The factory service manual has some goofy instruction to check the VSS by jacking rear wheels and running truck in gear and the "scan tool" should read the MPH and match the speedo. Except the OBD1 scan tool only flashes codes using the check engine light....IT HAS NO READOUT SCREEN . It did correctly give me a 24 code, "VSS -open or short problems or park/neutral switch circuit problem. Well, no ****.

 

[motorhead327]

More pics

 

[motorhead327]

Last pic....

 

[Gordy_]

I have the exact same problem with my '89 Sierra. I think the plastic that holds the plug in place has flexed back causing a loose connection. I plan to pull it apart and get it fixed during the summer.

 

[Leeztruk]

This may be way out in left field, but how much play is in the output shaft of the transmission?

 

[PlayingWithTBI]

After two after market vehicle speed sensors, I am back to the OEM. I got one VSS from O'Reilly which buzzed and whined I took it out and filed down the pickup so it would quit buzzing. My speedo problem persisted

I wonder if those replacement sensors aren't correct. Here's one from my '88. It looks just like the OE one.

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It had backed out past the O-ring and I knew for sure I had tapped it against the housing shoulder for a good, square seal. See pics.

IDK how that can happen with the retainer tab bolted in place. I had to bend mine a little to get it positioned properly but, it works.

Except the OBD1 scan tool only flashes codes using the check engine light....IT HAS NO READOUT SCREEN . It did correctly give me a 24 code,

Get a real scan tool, not a code reader. Here's an example using a laptop but, you can get a used Snap On "Red Brick" online pretty cheap.

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HTH