blazer

98  s 10 Chevy blazer got code po753 changed solenoids dose shift better and shift great but still getting code clear it and comes right back transmission fluid looks great iv worked on chevys all my life just not the newest stuff did test wires at solenoid with test light and it shifts great just can't get light to stay off thanks  

The solenoid may test good at the solenoid but there could be an open or high resistance on the control wire going back to the PCM. That's a good thing, the code setting immediately - it means a hard fault so you should have no trouble finding the issue.

so what am I looking for I got wiring diagram for pcm it shifts great so what do u mean to do what on return wire when I test lighted the other wire at solenoid it made transfer case click or something around there so didn't check it again but u saying to check return wire at pcm with test light or volt meter sorry I'm just learning thez years thank u for your time and help

Take some voltage measurements on the control wire at the computer and see if they agree with the command, if the shift solenoid is supposed to be on, make sure it reading low voltage, and when it's off make sure the voltage returns to battery or open circuit voltage. Compare reading with a known good shift solenoid control wire.

If you have bidirectional scanner see if your command agrees with voltage readings.

Use your test light and manually ground the wire at the computer and listen for clicking at the solenoid. Unplug the battery and ohm the entire circuit from the fuse to the control wire at the computer and compare to a good circuit. If the computer's still throwing a tantrum, cut the wire where you can easily fix it, at the control wire in question and cut the wire of a good control wire and temporarily swap them around. If you're still getting the exact same code, well it's got to be a bad computer then.

Any change if you remove and reconnect battery? If you get down to cutting wires, put your ammeter in series and check current too.

ok I found a ground going to back of head very light the test light when I do the ground to return wire only on one of the light green wires there 2 of them any how it show to be a ground an there no way to get back of head what would happen if gust run new wire to computer from motor can tell if there any other grounds tied in to that wire passenger side look to be just a ground strap from what little I can see in mirror driver side can't see nothing thank u very much for the help much needed rick

that didn't work with in a block of driving it right back on so not sure what to try now didn't do om test yet had to put it all back together need it tomorrow so I'll go back at it again soon as can both green wires was very bright like should be but as soon as hook a ground wire it went right out so thought I had it solve guess not

wrote:

ok I found a ground going to back of head very light the test light when I do the ground to return wire only on one of the light green wires there 2 of them any how it show to be a ground an there no way to get back of head what would happen if gust run new wire to computer from motor can tell if there any other grounds tied in to that wire passenger side look to be just a ground strap from what little I can see in mirror driver side can't see nothing thank u very much for the help much needed rick

I don't understand

Please disregard my testing method of cutting wires lol. That's not a good idea. There's a better one on identifix:



Leaving the solenoid on like that's a good test to see if it goes open from extended current flow. Thanks to Ralph for this test. This should negate having to do stupid ohm checks.

See attachment from tech help from iatn as well:
 

 

ok I did all test this time in getting 11.75 volts on green a yellow wire green 1/2 yellow 2/3 11.75 to ohm test show good did hear clicking when ground with test light at transmission but it was clicking spider pump tho and I do have a snap on brick I'm learning how to use it only had it a few months now just made a smoke mechanic last night been. chasing a vacuum leak to I believe any how it runs great but roughly idle now to day I noticed it smoke at start up it light white or blue so now it either intake gasket no water in oil yet or gas smoke wasn't standing behind it but plan to cold start it starts fast so not think it drains down on gas only time will tell but back to transmission is it in open loop on transmission it shifts great run 1500 to 1800 at 55 or around there 60 1900 don't won't to trash transmission buy running it around if it kinda my only cheep rid at this point the amps test I only got 1 at 20 mil amps any thing lower didn't read any thing maybe a video would help see what I'm doing wrong until next time thank a million rick

didn't hear clicking. crazy phone