Hard shifting

Tiny
RODDNEY KINCAID
  • MEMBER
  • 2002 SATURN SC1
  • 1.9L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 190,000 MILES
Hi, when you put in reverse it slams and also when put in drive slams. Also when driving in drive the gear changes are also slamming in to gears. I replaces vale body with a remanufactured tested on and have same slamming hard shifts in reverse and drive through all gears.
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Wednesday, November 18th, 2020 AT 7:12 PM

15 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Have you checked for diagnostic trouble codes that are related to the transmission? I ask because it can be a few things. First, there could be a line pressure issue. Also, the fluid level could be low, but I assume you checked that after refilling when replacing the valve body. There is also a line pressure regulator. The pressure regulator valve controls line pressure to provide the correct pressure to apply clutches. If it is too high, you will get hard shifts. (Pic 1)

So, what I suggest is to check line pressure to see if it is within spec. Here are the directions for testing. Pics 2 and 3 correlate with the directions.

________________

2002 Saturn SC1 L4-1.9L SOHC VIN 8
Line Pressure Test
Vehicle Transmission and Drivetrain Automatic Transmission/Transaxle Testing and Inspection Component Tests and General Diagnostics Line Pressure Test
LINE PRESSURE TEST
LINE PRESSURE TEST

pic 1

IMPORTANT: Be sure to perform both "Stepped Pressure Test" and "Maximum/Minimum Pressure Test" of the "Line Pressure Test."

STEPPED PRESSURE TEST
1. Run engine to bring transaxle to running temperature of 70 C (158 F).
2. Turn engine off.
3. Remove transaxle fluid temperature sensor and install pressure gauge.
4. Reinstall temperature sensor in wire harness.
5. Connect the Scan tool.
6. Key On engine Off. On first menu selection, select "Special Functions."
7. Select Line Pressure.
8. Transaxle in Park.
9. Scan tool will prompt you to start engine.
10. Select Run and the test will begin. The test will set engine speed to 1500 rpm and command line pressure up in steps from 396 - 1518 kPa (57 - 220 psi) in 100 kPa (15 psi) intervals.
11. As test is in progress, watch the gauge to assure the gauge readings follow the commanded pressures. Use a dry erase marker to mark the face of the gauge because it will be difficult to record the readings in time.

Pic 2

MAXIMUM/MINIMUM PRESSURE TEST
1. Oil pressure maximum and minimum values at idle should be checked using the following procedure:

IMPORTANT: For proper reverse operation, it is important to have at least 1206 kPa (175 psi) of system pressure in reverse at 70 C (158 F).
- With gauge connected and bans at operating temperature.
- With engine idling in Park, line pressure should be 400 - 600 kPa (58 - 72 psi).
- Remove line pressure fuse (10 amp TRS LP) UHJB.
- With engine idling in P (Park), pressure should be 1206 - 1690 kPa (175 - 245 psi).

NOTE: High value may be slightly lower if transaxle temperature is greater than 110 C (230 F).

IMPORTANT: With engine in Park, and the 10 amp TRS LP line pressure fuse removed. Minimum pressure should be 1206 kPa (175 psi).

2. Remove pressure gage, install temperature sensor, use Saturn P/N 21485278 sealant with Tenons on threads (or equivalent). After the sensor has been connected, clear diagnostic trouble codes caused by having the sensor disconnected.
Torque:
Sensor - Transaxle Fluid Temperature Sensor-to-Case: 8 Nm (71 inch lbs.)

________________________

Let me know if this helps or if you have other questions.

Take care,
Joe
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Wednesday, November 18th, 2020 AT 8:00 PM
Tiny
RODDNEY KINCAID
  • MEMBER
Have no line pressure tester and no good scan tool have cheap obd 2 scanner $20.00 one. So if line pressure to high or to low what would solve line pressure issue could also it be input output shaft nuts loose or wiring issue? I had to splice and replace bus plate connection plug do to lp wires were cut and 2 shift solenoid wires where cut at connector plug to bus plate was stuck in 4th gear. Before I fixed wiring and was not hard slam into reverse until after I fixed wiring? Also just replaced valve body with one off online.
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Wednesday, November 18th, 2020 AT 8:42 PM
Tiny
RODDNEY KINCAID
  • MEMBER
Also when I replaced the wiring harness to bus plate the red and blue lp solenoid wire connection in both bus plate and plug to bus plate were completely fried. Could it have burnt pins in PCM for lp solenoid? The lp fuse is good and did not blow if so will PCM cause issue for hard shifting? This is old bus plate and harness sense didn't blow lp fuse could it have went straight to PCM?
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Wednesday, November 18th, 2020 AT 9:12 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

As far as a control module being the cause, yes it's possible. In all honesty, without scanning the system with a scan tool that can read all types of codes, this becomes a guessing game.

As far as the pin being burnt, that certainly could have caused a problem but since it is to the IP, I don't think it is causing this issue.
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Thursday, November 19th, 2020 AT 6:21 PM
Tiny
RODDNEY KINCAID
  • MEMBER
I have no codes coming on my obd 2. There was until I replaced wiring loom then all codes went away. Could engine mounts cause the so called reverse slam these cars have?
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Thursday, November 19th, 2020 AT 6:32 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If you have a bad mount, I could see it causing a clunk or noise, but I don't feel it would cause it to slam into gear.

Can your OBD2 scan tool read transmission codes?

Joe
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Thursday, November 19th, 2020 AT 6:57 PM
Tiny
RODDNEY KINCAID
  • MEMBER
It threw 3 transmission codes 1 lp 2 shift codes. But that was because wires were cut when I bought car. Since I replaced wiring two transmission codes went away, but then started the slam into gear.
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Thursday, November 19th, 2020 AT 7:27 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I suspect it is something to do with line pressure. I would see if you can get your hands on the gauges needed to check line pressure and follow the directions I listed above.

Is that something you feel comfortable doing?

Joe
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Thursday, November 19th, 2020 AT 7:51 PM
Tiny
RODDNEY KINCAID
  • MEMBER
I can rent one from AutoZone, but what is going to tell me that pressure to high or to low and what is the fix for high or low line pressure replace of lp solenoid or something further the valve body? I bought online says was tested so should be good at solenoids. Is there something else for the lp that could cause high or low lp pressure?
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Thursday, November 19th, 2020 AT 8:03 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
If it is too high or low, the pressure regulating valve needs to be inspected.

If I had the vehicle, that is the next thing I would check simply because this is a typical characteristic of high pressure. I can't guarantee this is the problem, but we need to start at some point.

Joe
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Thursday, November 19th, 2020 AT 8:11 PM
Tiny
RODDNEY KINCAID
  • MEMBER
So pressure regulator valve is locates bottom of valve body slides in and out with little metal bar that connects to it, correct? So, valve body I got online came with one and old valve bod has one. So the both could be bad?
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Thursday, November 19th, 2020 AT 8:43 PM
Tiny
RODDNEY KINCAID
  • MEMBER
So we know lp is probably to high witch may be causing the slam engagement when put into reverse also into drive and up shift as well as down shifting lp has pressure regulator valve has lp solenoid and lp fuse witch goes to PCM so if terminals are fried in PCM will this cause issue dew to PCM not sending right signal for regulated lp pressure what else has to do with the line pressure?
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Thursday, November 19th, 2020 AT 8:50 PM
Tiny
RODDNEY KINCAID
  • MEMBER
Can you send pictures of pressure regulator valve replacement? Also after install of valve body does PCM need to relearn the transmission and if so how long does PCM take to readapt to transmission?
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Friday, November 20th, 2020 AT 7:00 AM
Tiny
RODDNEY KINCAID
  • MEMBER
Can VSS cause slam while sitting and shifting into reverse at idle?
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Friday, November 20th, 2020 AT 7:01 AM
Tiny
KEN L
  • ADMIN
Those burnt pins don't look good. I would fix those first also let us know what color are the wires so we can see what they go too.
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Saturday, November 21st, 2020 AT 7:40 AM

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