where is the shift/timing solenoid on a 98 gmc sonoma 2.2 automatic?
- Thread starter Scotty
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Molson02536
New member
The shift is controlled by the ECM from inputs from the TPS, transmission out put shaft and input shaft. To change the shift points, your going to have to reprogram the ECM also know as Dyno Tune to your preference of performance of transmission shift points and firmness.
If you can find a transmission shop with a Tech2 scanner, you can have them recalibrate the transmission to shift at a lower or higher shift point and to raise the transmission line pressure to give it a more firmer shift.
You can buy a B&M electronic shiftpluse to give you a more aggressive shift for around $45.00 and take less then 30 min to install. You can also improve your 1-2 shift by replacing the servo with corvette servo's ($45.00) and you don't even have to drop the transmission pan to swap it out.
http://www.bmracing.com/SPECIALS/ShiftPlus-electronic-Shift-Improver-for-GM
Good luck and hope this helps.
If you can find a transmission shop with a Tech2 scanner, you can have them recalibrate the transmission to shift at a lower or higher shift point and to raise the transmission line pressure to give it a more firmer shift.
You can buy a B&M electronic shiftpluse to give you a more aggressive shift for around $45.00 and take less then 30 min to install. You can also improve your 1-2 shift by replacing the servo with corvette servo's ($45.00) and you don't even have to drop the transmission pan to swap it out.
http://www.bmracing.com/SPECIALS/ShiftPlus-electronic-Shift-Improver-for-GM
Good luck and hope this helps.
I have a 98 sonoma too. It shifts hard between 1-2, What would cause that? Thanks
Molson02536
New member
1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS
Or Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break.
These are the most common things that can cause hard shifts unless the previous owner of the Somoma had the Transmission recalibrate.
Put a line pressure gauge (or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a 0.490" boost valve (easy fix in pan).
Work good in all other shifts, OD works good too, Thanks For your info.1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS
Or Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break.
These are the most common things that can cause hard shifts unless the previous owner of the Somoma had the Transmission recalibrate.
Put a line pressure gauge (or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a 0.490" boost valve (easy fix in pan).
Molson02536
New member
Forgot, check your transmission fluid level when it's at operating temperature. Low fluid will give it a harder 1-2 shift, the EPC is compensating for the lack of fluid by raising the transmission line pressure.
No worries though, common for the 1-2 shift to be firmer then the others on the 4L60E due to it's very low first gear. 