Service engine soon light

gmbwrenchn · #1 10-12-2004, 06:37 PM

97' Blazer w/108k miles. 4Wheel drive. Automatic trans. Pulled out of my driveway today and not more than a mile away the service engine soon light popped up and it felt like the trans. was slipping with the rpms fluctuating all over the place. If I start from a stop, in drive it feels like it's slipping, if I start in 1st or 2nd it takes off fine but I felt no shifting occuring. Tried to engage the 4 wheel drive but it felt like it never engaged. This happened for 25 miles this morning. Got out of work 8 hrs. later, drove home, {25 miles} and there was NO slipping or rpm fluctuating either. It shifted fine all the way home.......BUT the service engine soon light is still on. Any ideas what this problem is would be appreciated.

Mikado14 · #2 10-12-2004, 07:52 PM

You need to have the truck scanned and retrieve the code.

gmbwrenchn · #3 10-12-2004, 08:20 PM

Thanks, will do and report back.

BlazerLT · #4 10-12-2004, 11:10 PM

Yes, get it scanned at AutoZone and come back here with the exact codes so we can help you.

quaddriver · #5 10-13-2004, 11:20 AM

screw autozone, you need someone with a scanner that can talk to the PCM and pull tranny codes. the tranny you have is the 4L60E and what you are likely having is a sticking shift solenoid allowing a clutch to not apply. that fact that it worked when warm indicates that there is a lot of gooey gunk in the passages - most likely from the torque converter clutch going. Im afriad this is most likely gonna require a trans disassembly at the very least to clean this out. Maybe you will get likely and an offending solenoid can be replaced....but you would be in the minority.

At autozoen or advance all they are going to be able to do is say 'you have Pxxxx' which is pretty much useless.

BlazerLT · #6 10-13-2004, 02:17 PM

Quote:

Originally Posted by quaddriver

screw autozone, you need someone with a scanner that can talk to the PCM and pull tranny codes. the tranny you have is the 4L60E and what you are likely having is a sticking shift solenoid allowing a clutch to not apply. that fact that it worked when warm indicates that there is a lot of gooey gunk in the passages - most likely from the torque converter clutch going. Im afriad this is most likely gonna require a trans disassembly at the very least to clean this out. Maybe you will get likely and an offending solenoid can be replaced....but you would be in the minority.

At autozoen or advance all they are going to be able to do is say 'you have Pxxxx' which is pretty much useless.

So what, it is free and they can extract all the codes so we can help him narrow the problem down.

gmbwrenchn · #7 10-13-2004, 06:55 PM

Let's all try to get along children. Went to AUTOZONE AND GOT THE CODE. Drove out there about 10 miles COLD ENGINE. Service light was STILL ON and trany and rpms were fine. Got the code. PO740, 1 OF 4 it said. Also said something about a circuit malfunction. Drove it home, light was on for five miles, now it went off. Everything seems to be fine. Autozone could NOT get the code discription for me either. Thanks.

quaddriver · #8 10-13-2004, 07:09 PM

P0740 is the lockup clutch in the converter circuit.

Interestingly you said it happened cold, the TCC aint supposed to lock up cold. Typically 12v is always supplied hot when key is on, and the PCM supplied the ground, so if this is truly the problem then you have a short to ground in the solenoid which is fairly easy to fix but requires droppin a pan.

However, there is also a problem where the valve body separator plate goes and crossbleed applies the clutch without a PCM signal.

gmbwrenchn · #9 10-13-2004, 08:17 PM

So should I start by dropping the pan and replacing the solenoid? Do are friends at AUTOZONE have this part? What EXACTLY should I ask for. I want to do this myself and some breif instructions on what to look for and how would be appreciated.

BlazerLT · #10 10-13-2004, 08:49 PM

P0740 Torque Converter Clutch Circuit Malfuction

The switch is not locking up.

gmbwrenchn · #11 10-13-2004, 11:53 PM

So what next?

gmbwrenchn · #12 10-14-2004, 05:50 PM

What would you do next?

BlazerLT · #13 10-14-2004, 07:00 PM

This is a tough one seeing I have no knowledge on this matter but I would go a talk to a transmission shop and see what can be done or even talk to the GM shop to see if there is a recall on it.

barpat96 · #14 10-14-2004, 08:41 PM

this sounds like a problem i had last month. it turned out to be in the ignition box. Metal contacts had carbon build up

barpat96 · #15 10-14-2004, 08:44 PM

I had it scanned at autozone and the following codes came up. P0740, P1860, P0753, P0785, P0758
Autozone employee was an idiot but the codes sure did help out. You can replace the wiring harness for about 125.00 but im to cheap so i just took it apart and cleaned off the contacts(it takes patience)
Good luck

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