John6275

I have a 1999 Tahoe 4x4 5.7 V-8 automatic
Started to go hunting it would not shift out of 1st or 2 gear. Never had this problem before.
Speedometer is not working and check engine light is on as well as ABS light. I checked codes and it was 502 code which is supposed to be speed sensor. I replaced the speed sensor as it was a quick and rather inexpensive fix.
It is still doing the same thing.
I have read some stuff hear but was hoping someone had actually experienced this and fixed it.
Thanks for any help.

chevy55

could be faulty or corroded wiring in the speed sensor circuit.i have repaired issues like yours and the customer had two front wheel speed sensors changed by a dealership and it didnt fix the issue.i found the wiring to the abs controller in the connector for the speed sensor circuit had corroded in the connector.i cleaned up the green corrosion and the issue was resolved.yours may be different,but i would check all the wiring in the abs circuits for any sign of corrosion.mainly check all connectors.hope this helps.

John6275

Are you talking about where the ABS sensors contact at hubs or other locations?

John6275

I'm still needing help on the issue with Tahoe
1999 model 4x4
Code 502, want shift out of first unless I do it manual. Doing it manual it will do 1st and 2nd
If it's in drive or 3rd it want shift out of first. Speedometer stopped working and ABS antilock light on all at same time.
Replaced speed sensor. Didn't fix. Checked wires and connections to sensor and tranny but found nothing.
I have now cleaned ABS sensors on both front hubs. Reset codes but still doing all of same things.
Could really use some help.

chevy55

did you check the wiring at the abs control module.all the vehicle speed sensors all go through the abs control module then to the ecm then to the instrument cluster.you must have a broken or coroded wire in the speed sensor circuit.it takes time to find electrical issues.if you lived up where i live i would be more than happy to help you.

chevy55

did you manage to get a complete schematic of your complete abs and speed sensor circuit.a proper schematic of your speed senor circuits will help you narrow it down.

John6275

Update, bought one speed sender and rotated/changed out all three (yes there are three and they are all the same part) one on right rear and two on left. Tried unplugging unit behind glove box as well as passing gear cable inspection with no luck. Took it to atranny shop I've had good luck with. They confirmed electrical and referred me to a shop that does a lot if that. Dropped it there and they found broken plug on top of tranny where there is a coupling of shorts of the harness. Prob didn't take them 5 min since they had it on lift. They wanted $375 to replace the plug before they could be sure that was only problem. So $113 for something I didn't find. Went to pull a part and got plug (same type as those on vss) spliced it in and everything works again. Hope this helps someone else.

Goins Mark

My 2005 Silverado 2500hd 4x4 will not take any gear it has plenty of fluid in it just wont go in any forward gears or reverse