So my '99 blazers "service engine soon" and "service 4wd" light are both on. I called up my local chevy dealership asking how much it would cost to get a engine diagnostic etc. and I was told $110 ($220 for both). Now I don't want to pay $220 to find out I need to sped another $1,000 to fix the d**n thing.

I know my transmission is going (shifts hard into 2nd after driven for over a hour, changed tranny fluid and found metal in the pan) so I need some advise on what I should do. I just want to get it drive-able because I'm gettingshipped out this summer and I'm going to be trying to sell it.

Any advise!!!????!!!!

 

Moving to General Tech. And one post is all that is necessary...

Autozone could tell you what the SES light means, as for the 'Service 4wd' light, well... Does your truck have Auto4wd? I'm assuming it does.

 

Yes, I know that autozone does it for free... they got the code "OBDII (Alpha) P Code P1870"
(Tranmission automatic 4-wheel drive indicator (lamp) circuit short to battery)
(Tranmission mechanical transfer case 4x4 switch circuit short to battery)

The codes mean nothing to me because I don't know what they are saying... and I don't full trust what they computer says.
Yes, it does have auto 4wd.

Should I invest and at least get the "service 4wd" checked on?

 

P1870 means "transmission component slipping".

Here's A TSB that might apply to you.
A/T - 4L60-E Harsh 1-2 Gear Upshift/MIL/SES/CEL ON

File In Section: 07 - Transmission/Transaxle
Bulletin No.: 01-07-30-023B
Date: March, 2002
TECHNICAL
Subject:
Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set
(Replace Valve Body)

Models:
1996 Buick Roadmaster
1996 Cadillac Fleetwood
1999-2000 Cadillac Escalade
1996-2000 Chevrolet Camaro, Corvette
1996-2000 Pontiac Firebird
1996-2000 Chevrolet and GMC Light Duty Truck Models
1996-2000 Oldsmobile Bravada
with 4L60-E Automatic Transmission (RPO M30)
Built Prior to January 15, 2000 (Julian Date 0015)

This bulletin is being revised to update VIN Breakpoint Date information and revise the Parts Information table. Please discard Corporate Bulletin Number 01-07-30-023A (Section 07 - Transmission/Transaxle).
Condition
Some customers may comment on a harsh 1-2 upshift and the Check Engine Light or Service Engine Soon indicator is illuminated.
Diagnosis
Typically, these vehicles will have been driven more than 32,000 km (20,000 mi) before this condition occurs.
The scan tool may show a DTC P1870 set as a history code.
A harsh 1-2 shift or DTC P1870, caused by wear in the control valve body, may be difficult to duplicate when the transmission temperature is below 93°C (200°F).
Cause
The condition may be due to wear in the control valve body. This wear occurs in the bore that contains the TCC isolator and regulator valves, and results in poor, or no, TCC apply.
Important :




^
DTC P1870 is a type B code. The conditions for setting the P1870 DTC must occur on TWO CONSECUTIVE TRIPS (ignition cycles, with a drive cycle) before setting a P1870 history code.


^
When the conditions for setting DTC P1870 are met (first trip), the PCM commands maximum line pressure and harsh 1-2 shifts are the result.


^
This may result in a harsh 1-2 shift with no history code if the conditions for setting the DTC required for the second trip are not met, on two consecutive trips (Ignition cycles, with a drive cycle).


^
When the conditions for setting the DTC are met, on the second consecutive trip, a DTC P1870 is stored as a history code.


^
When the P1870 code is stored, the PCM will turn on the Service Engine Soon (SES), Check Engine Light (CEL), or Malfunction Indicator Lamp (MIL).

Correction
Install a control valve body with the revised TCC regulator and isolator valves. Refer to the Parts Information table below. These valves are used in all transmissions produced after January 15, 2000 (Julian Date 0015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves.
Important : If all of the following conditions are true, it is not necessary to rebuild the transmission or to replace additional transmission components beyond the control valve body.





^
Transmission operation is normal before the transmission reaches operating temperature, or before DTC P1870 is set (no slips, flares, or missing gears).


^
The torque converter

 

Thanks for posting all that up even though I've read it on other posts.

Who has installed a control valve body on there blazer? Is it hard to install? Is it internal in the transmission or is it on the outside of the transmission?
If it isnt too hard to do then ill give it a shot but if not... I don't know. Thanks again in advance

 

No it's not that hard to replace the valve body. you can do it without removing the transmission. Pop the pan off and it unbolts. Don't lose the check ***** and you can use vasilene to hold them in when you put them back. Also remember where the bolts came out because they are different sizes.You can either buy a new or rebuilt one or ream it out and fix it yourself. Here's a link to a place that sells what you need to fix a P1870 if it's not too worn out. Scroll down to about the middle of the page and you will see the P1870 code fix.

http://www.transmissioncenter.net/4L60E.htm