Good morning, I have a 1995 gmc 2500 with a 5.7L that goes into limp mode. I have taken it to couple of shops and no one can figure it out. I have taken it to the transmission shop and they say the transmission is fine. We have changed couple of sensors and the ecn as well. Can someone help me out to figure this problem out. Thanks
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Help 95 gmc 2500
- Thread starter joe956
- Start date
dbrannon79
I'm getting there!
Welcome to the forum @joe956 have you connected a scanner to see what codes are showing up? with a 95 that is an OBD1 system which you can also used the method of shorting two of the ALDL connector pins, turn the key on and count the SES light flashes. it'll flash long and short flashes giving you the code numbers. an example is on long followed by two short flashes would be code 12.
Here is a link on how to read them along with a small list of descriptions on each code.
mechanicbase.com
Post what codes you get and we will help you
Here is a link on how to read them along with a small list of descriptions on each code.
OBD1 Codes: Full GM Code List And How To Read Them
In this guide, we will go through everything you have to know about OBD1 Trouble Codes. Learn to read the trouble codes without a scanner and the meaning.
mechanicbase.com
Post what codes you get and we will help you
dbrannon79
I'm getting there!
usually trans codes won't turn the engine light on unless there is an issue with one of the engine sensors that also help control the trans like the TPS (throttle position sensor) if the trans is detecting a slip or torque converter issue, the light won't turn on but will go into limp.
one thing to consider is check and cleaning all of the grounds. battery, body, frame and ECM grounds. most all of the important ones are located under the hood. I know where they are located on the diesel rigs, but not so much on a gasser. look on and around the intake bolts for some smaller wires with eyelets bolted to the intake. for the 6.5 diesels they are located on the furthest most intake bolt near the trans dipstick tube (passengers side). they might be in other locations for gas rigs though.
one thing to consider is check and cleaning all of the grounds. battery, body, frame and ECM grounds. most all of the important ones are located under the hood. I know where they are located on the diesel rigs, but not so much on a gasser. look on and around the intake bolts for some smaller wires with eyelets bolted to the intake. for the 6.5 diesels they are located on the furthest most intake bolt near the trans dipstick tube (passengers side). they might be in other locations for gas rigs though.
dbrannon79
I'm getting there!
also one thing to note: OBD1 code readers are hard to come by nowadays. especially ones that can read trans and ABS systems. everyone here recommend investing into a GM Tech 2 scanner or the fleabay knock off replica of it. just don't ever try to update the knock off ones or they will stop working. the tech 2's can read that data and also read live sensor data from the older flavors that is good for diagnosing things like a failing sensor that hasn't gone out of whack enough to set a real code or wiring issues when seeing funky readings off sensors.
edit: check the main harness connector going into the trans. look for trans fluid seeping into the pins of the connector. that can cause sensor reading issues too.
edit: check the main harness connector going into the trans. look for trans fluid seeping into the pins of the connector. that can cause sensor reading issues too.
MrMarty51
Well-Known Member
ALDL connector below the steer wheel, under the dash. Bend a paper clip, short the A and the B terminals together with that paper clip.
Turn on the ignition switch. It will flash a code 12, that signals that the ECM is reading. It will flash that code 12 three times. If there is any other codes, it then will flash those codes, three times on each code then move to the next code.
Try that and see what happens.
Turn on the ignition switch. It will flash a code 12, that signals that the ECM is reading. It will flash that code 12 three times. If there is any other codes, it then will flash those codes, three times on each code then move to the next code.
Try that and see what happens.