speed sensor p0502 no speedometor 1996 suburban

[ritchie lee]

Driving home about 50 miles, with 10 miles to go. The speedometer quits, the ABS light comes on, and the transmission malfuctions ( appears to be in 2nd gear only). I managed to drive slowly home as is. When I get home turn off, restarting the check engine light is now on, able to retrive computer code P0502 (vehical speed sensor A circuit low input). The next day everything seem to work fine no check engine light, how ever I am still able to get P0502 code. I'm scared to drive this car to far from home. 1996 Chevy suburban, 5.7 vortec, 4wd 4L60E transmission. Help!
I'm thinking this speed sensor is either on the transmission or the transfer case.

[MT-2500]

Originally Posted by ritchie lee

Driving home about 50 miles, with 10 miles to go. The speedometer quits, the ABS light comes on, and the transmission malfuctions ( appears to be in 2nd gear only). I managed to drive slowly home as is. When I get home turn off, restarting the check engine light is now on, able to retrive computer code P0502 (vehical speed sensor A circuit low input). The next day everything seem to work fine no check engine light, how ever I am still able to get P0502 code. I'm scared to drive this car to far from home. 1996 Chevy suburban, 5.7 vortec, 4wd 4L60E transmission. Help!
I'm thinking this speed sensor is either on the transmission or the transfer case.

Speed sensor is on left rear of transpher case.
As with any code it does not say replace sensor but check it out.
First thing check wiring and plug in to it.

Let us know how it goes.
Ps code will need cleared with a scanner after the repair to make it go away.

[ritchie lee]

I'm still have an intermitent problem, works hot works cold, won't work cold won't work hot. Lately though the speedo has been more irratic, (a short somewhere?). Anyhow I have tested a new sensor, the terminals appear to be good. I tested the plug, and found the purple/white wire to be careing 4.75 volt, and a tiny bit gets through on the ohms scale when nothing is turned on. The green/black wire passed nothing ohms or volts whether on or off.
Maybe the grn/blk wire bad, this must go to the computer.
Oh and one more thing now I'm getting a P0500 code. Sometimes a P0500 & a P0502 I guess it depends on the moon or stars.
127,000 and no other recent codes.
Thanks for the help.

[MT-2500]

Originally Posted by ritchie lee

I'm still have an intermittent problem, works hot works cold, won't work cold won't work hot. Lately though the speedo has been more irratic, (a short somewhere?). Anyhow I have tested a new sensor, the terminals appear to be good. I tested the plug, and found the purple/white wire to be careing 4.75 volt, and a tiny bit gets through on the ohms scale when nothing is turned on. The green/black wire passed nothing ohms or volts whether on or off.
Maybe the grn/blk wire bad, this must go to the computer.
Oh and one more thing now I'm getting a P0500 code. Sometimes a P0500 & a P0502 I guess it depends on the moon or stars.
127,000 and no other recent codes.
Thanks for the help.

Code 500 is speed sensor circuit problem.
Code 502 is speed sensor low input to VCM.
502 indicates you are losing or input to VCM is dropping off/down.

You need to test the sensor input to VCM when it is acting up.
Could be bad wiring or bad sensor or plug in.
Good and Best and fast way to test is a scanner read out when it is acting up.
Or with a good high end volt/ohm meter measure signal to VCM at 50-60 MPH when it is working and when it is acting up.

And remember when checking low or computer voltage do not use a old resister type volt/ohm meter.

If good same voltage to VCM when it is working and when acting up then your problem is VCM or cluster.

If voltage is dropping when acting up then trace wiring back to speed sensor.

[j cAT]

Originally Posted by ritchie lee

Driving home about 50 miles, with 10 miles to go. The speedometer quits, the ABS light comes on, and the transmission malfuctions ( appears to be in 2nd gear only). I managed to drive slowly home as is. When I get home turn off, restarting the check engine light is now on, able to retrive computer code P0502 (vehical speed sensor A circuit low input). The next day everything seem to work fine no check engine light, how ever I am still able to get P0502 code. I'm scared to drive this car to far from home. 1996 Chevy suburban, 5.7 vortec, 4wd 4L60E transmission. Help!
I'm thinking this speed sensor is either on the transmission or the transfer case.

remove the connector to the VSS/transmission speed sensor. measure the sensor resistance it should be in the 2oooOHM range.....

my guess is this sensor needs replacement. first remove and see if the VSS part inside the transmission has debris on it.....

if this all checks out remove the connectors to the PCM/vehicle computer to see if the connector pins have corrosion or the wires got chewed up by rodents etc...

[ritchie lee]

K I have got this fixed, so far.
I tested the wires at the vss plug to the computer. I unhooked the BLUE socket/plug at the computer, looking for #29 & 30 green/black & purple/white. The grn/blk was dead when tested with an ohm meter, the other wire #30 ppl/wht was ok. Started trying to follow the wire back from the vss, about 18 inches was a 2wire plug (grn/blk, ppl/wht) that went in to a double ended socket, un hooked it here. Tested both wires one was good and the grn/blk was dead. I could not get the grn/blk wire out of this harness. It was up high and hard to get at stated tugging and trying to get the tape off these wires to get it loose, the grn/blk wire came apart about 2 inches away from this plug. I repaired this wire with a unisulated crimp on connector. I used liquid tape on the connector and covered it with shrink tube. Wish i was able to solder it though. Retested the wire it was working. YeeHa! I was almost certian I had it fixed, drove it around the block, the speedo worked instantly. Drove to work today about 5 miles working fine.
I have been lurking in this group for about a year now I like to do my own work. AC, intake, Fpump, ergvalve, so far.
Thanks for all the help. Hope this might others.
RL

[MT-2500]

Originally Posted by ritchie lee

K I have got this fixed, so far.
I tested the wires at the vss plug to the computer. I unhooked the BLUE socket/plug at the computer, looking for #29 & 30 green/black & purple/white. The grn/blk was dead when tested with an ohm meter, the other wire #30 ppl/wht was ok. Started trying to follow the wire back from the vss, about 18 inches was a 2wire plug (grn/blk, ppl/wht) that went in to a double ended socket, un hooked it here. Tested both wires one was good and the grn/blk was dead. I could not get the grn/blk wire out of this harness. It was up high and hard to get at stated tugging and trying to get the tape off these wires to get it loose, the grn/blk wire came apart about 2 inches away from this plug. I repaired this wire with a unisulated crimp on connector. I used liquid tape on the connector and covered it with shrink tube. Wish i was able to solder it though. Retested the wire it was working. YeeHa! I was almost certian I had it fixed, drove it around the block, the speedo worked instantly. Drove to work today about 5 miles working fine.
I have been lurking in this group for about a year now I like to do my own work. AC, intake, Fpump, ergvalve, so far.
Thanks for all the help. Hope this might others.
RL

You are welcome and thanks for posting back how it went.
Yes posting back the fix often helps others.

Good find and good repair work.

If you need any more help just run a New thread.

If you are going to be doing a lot of your own work it might pay you to get some good repair information.
Like a factory service manual or a All data DIY online sub.
Good Luck

[kc5nqx]

Ok I am having same symptoms my question is crawled under suburban an at the rear of tease I have two of the same vss sensors one on the passenger side an one on drivers screw in type which one do I check???

[MT-2500]

Originally Posted by kc5nqx

Ok I am having same symptoms my question is crawled under suburban an at the rear of tease I have two of the same vss sensors one on the passenger side an one on drivers screw in type which one do I check???

Best to start your own New/Thread post on your problem.
And give all info on yours.
What it is doing or not doing
Year make and model and engine and transmission and 2 or 4 W