Question about 1998 GMC Jimmy
This GM service bulliten might apply to your vehicle:
TSB # 01-07-30-023A
Harsh 1-2 Upshift, SES, MIL, or CEL Illuminated, DTC P1870 Set (Replace Valve Body)
1996 Buick Roadmaster
1996 Cadillac Fleetwood
1996-2000 S10 Blazer
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, 1999 (Julian Date 9015)
This bulletin is being revised to update the Parts Information
Please discard Corporate Bulletin Number 01-07-30-023 (Section 07 -- Transmission/Transaxle).
Some customers may comment on a harsh 1-2 upshift and the Check Engine Light or Service Engine Soon indicator is illuminated.
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).
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
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).
Install a control valve body with the revised TCC regulator and isolator valves. These valves are used in all transmissions produced after January 15, 1999 (Julian Date 9015), and all of the service parts currently available through GMSPO contain revised TCC regulator and isolator valves.
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 is not blue or overheated.
The transmission fluid is not burned or has no burned odor.
The transmission fluid pan contains no abnormal debris (clutch material, bronze, brass, or metal fragments
Posted on Jun 18, 2010
I have a 98 chevy s-10 blazer with 155,000 and has been maintained regulary and i have read about the p1870 code and the answer i can't seem to find is that where is the control vaulve body exactly located and how and where do i install it?...i have the same problem with the hard shifting after it has been driven atleast 50 miles.
Posted on Jun 30, 2010
Trans slip code check your levels when warm top up but the trans may need to be overhauled if it persists, it will get worse!
Posted on Jun 18, 2010
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
Here's a link to this great service
Posted on Jan 02, 2017
Tips for a great answer:
Sep 14, 2015 | Buick Cars & Trucks
Nov 28, 2012 | 2000 Pontiac Firebird
Mar 14, 2012 | 1998 Honda Passport
Sep 13, 2011 | Chevrolet S 10 Cars & Trucks
Sep 22, 2010 | 1997 Pontiac Grand Prix
Aug 15, 2010 | 1999 Chevrolet Lumina
Jun 21, 2010 | 1999 Chevrolet Silverado 1500
Apr 18, 2009 | Chevrolet Lumina Cars & Trucks
Apr 16, 2009 | Oldsmobile 88 Cars & Trucks
5,694 people viewed this question
Usually answered in minutes!