Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Is there a way to test your 4x4 actuator in a 2002 Silverado to see if it is actually working? I have replaced it with a new actuator and new transfer case control switch and still cannot get my truck to go into 4x4. Switch just blinks and blinks 4hi or auto. I also have changed wires to make sure of bad wires. No idiot lights on either. I am wondering if my new actuator is not working properly. A while back when the old actuator was in, I pulled the skid plate and tapped on the actuator and it started going into 4x4 like a new one. So I thought for sure the actuator was my culprit.
I have supplied power and ground to this actuator before just briefly to make sure it works properly. You don't want to hold power and ground there too long as it can turn the motor/actuator too far and then it would have to be replaced.To do this I located the fatter black and fatter red wire and provided a ground to the black wire and touched power to the red wire and it should move if it is working.If it is working then the fault may be with the transfer case control computer itself as I have seen old actuators short out internally and then feed back this short to the transfer case computer and short it out as well.The fault codes should be checked as well in the transfer case computer with a scan tool that can communicate with this computer to see what codes have set as this will aid in the diagnosis. A local parts store might check the fault codes free of charge as I have heard of before.Let me know if you need anything else. Thanks! Happy Holidays!
I don't understand where these wire are that you are talking about. There are no red wires on my actuator plug. Cant I just turn the actuator out, plug it in, start the truck and hit the button and it should turn?
Is this the transfer case actuator you are speaking of or the front differential actuator?
Front differential, the one that engages the 4x4
Ok. You can check this by removing it from the front differential, then start the vehicle and try and engage the 4wd. It should move out when engaged and move back in when disengaged.There isn't a way to really jump power and ground to this actuator as it can damage this unit causing it to be replaced.The most common component to fail on this vehicle that I have seen several times before is the transfer case electric shift actuator as it can fail internally electronically. When this actuator doesn't engage properly the front differential actuator won't engage properly as well.From what you have described here the transfer case actuator sounds like what you may have at fault as it is very common to cause this issue here.I would still have the fault codes checked in the transfer case computer by a scan tool or code reader that can communicate with this computer to see what codes have set. Then from there it can be diagnosed as to what component is at fault and needs replaced.Let me know if you need anything else. Thanks! Happy Holidays!
Testing the actuator the way you described. If I hit the 4hi button inside the truck, would the 4hi button actually quit blinking and say it is locked into 4hi (if the actuator is functioning properly)? I have tested both the old and new actuator and neither of them seem to be working. Is it going to be very obvious when they are moving in and out?
Yes once the cycle is complete, meaning once first the transfer case actuator cycles to 4 high (which you should be able to hear coming from under the centre of the vehicle as it is very noticeable) and then the front differential actuator engages the light quits blinking and stays lit in 4wd hi. Same as when you switch back to 2wd you can hear the motor on the transfer case and then the front actuator will move as well and the light will quit blinking and stay lit in 2wd.If you do not hear the noise from the transfer case which should be heard with your driver's door open when pressing 4high then this can indicate the actuator on the transfer case is faulty and needs replaced.But the fault codes should be checked first to verify this is at fault as well as some testing from the fault code that is set.Let me know if you need anything else. Thanks! Happy Holidays!
There are no check engine or service 4wd lights present on my truck. I can hear the noise you described coming from the centre of the vehicle but the front differential does nothing. I also want to add that this truck has only 50k miles.
It would be obvious when the actuator moves in and out for the front differential.If you hear the transfer case motor engaging and disengaging then the front actuator should move as well unless there is a fault with the new actuator or a fault with the transfer case computer which is possible since the vehicle does have a 4wd fault but isn't giving you any messages on the dash as there should be a 4wd message letting you know there is a fault detected and a faulty computer wouldn't see the fault to turn on this message.Even at low miles I have seen the 4wd computer fail internally and need replaced as well as other components for the 4wd system fail like the actuator on the front diff. and on the transfer case.The best thing to do is to have the fault codes checked just to make sure the 4wd computer hasn't set any codes and to make sure communication can be established with the 4wd computer with a scan tool that has this capability to see if it is the computer at fault here.Let me know if you need anything else. Thanks! Happy Holidays!
I am going to go pick up another new front differential actuator and just plug it in and see if it will engage. I hate to keep throwing money at the problem. My local napa is good about returning parts for troubleshoot as long as they are not special order. If this doesn't work then I will have to see about getting scanned.
Throwing parts at a vehicle is never a good option to try and resolve it. This is why it is best to have the fault codes checked and to have it tested to see if there is another component at fault like the 4wd computer or possibly the actuator on the transfer case even though it is moving as heard moving.GM does have a bulletin out on some of these for the transfer case actuator sensor failing internally and confusing the computer on what gear it is selected in and their correction was to remove the transfer case motor and take it apart and replace this sensor. You would usually have a fault code set if this is the case though.Let me know if you need anything else. Thanks! Happy Holidays!
Thank you for all your help. Plugged in another new actuator and still nothing. I am going to get this thing hooked up to a scanner and see what I can find. Do you have a part number for the 4x4 computer and where is it located? Simple to install?
The control module is located behind the shift switch and headlamp switch assembly. You have to remove these switches to gain access to it. The part number varies by your vehicle's VIN number and this control module also has to be programmed by a dealer with their scan tool and computer for it to operate properly after words.You might check with a local parts store as they may sell these pre-programmed ready for install. It usually takes about an hour to replace it and is a tight fit inside the dash. The cluster and switches on the drivers side of the dash have to be removed in order to access and replace this module.Let me know if you need anything else. Thanks! Happy Holidays!
Thought I would let you know that I have found the culprit. I chased the main harness that goes to the transfer case, trying to find a ground. I found one mounted to the cab mount. I pushed the 4hi button and wiggled the wire and bingo the front actuator engaged. It wasn't broken or loose but I think there was some corrosion in the wire strands. I cleaned and re-taped it up and now it works like a charm. All these parts and all I needed was a wire brush and some black tape.
Glad to hear the fault has been located and repaired. I didn't mention checking wires as in your question you had posted the wires had been checked but a loose or faulty ground connection can cause this for sure.Let me know if you need anything else. Thanks! Happy Holidays!