This is straight from the TM-34
[FONT="]NO UPSHIFTS, DELAYED UPSHIFTS, OR FULL THROTTLE UPSHIFTS ONLY[/FONT]
[FONT="]Step 1. Disconnect downshift electrical connector from side of transmission. Operate truck[/FONT]
[FONT="]and observe upshift performance.[/FONT]
[FONT="]If upshift is normal, replace transmission downshift switch on side of[/FONT]
[FONT="]accelerator bracket.[/FONT]
[FONT="]If upshift performance is still poor, perform step 2.[/FONT]
[FONT="]Step 2. Connect downshift electrical connector to side of transmission. Test transmission oil[/FONT]
[FONT="]pressure with brakes applied, “ D“ (Drive), engine at 1000 rpm. (See paragraph[/FONT]
[FONT="]5-11)[/FONT]
[FONT="]If oil pressure is normal; remove, disassemble, clean, and inspect governor[/FONT]
[FONT="]assembly. (See paragraph 5-5)[/FONT]
[FONT="]If oil pressure is high, perform step 3.[/FONT]
[FONT="]Step 3. Test transmission oil pressure with brakes applied, “N” (Neutral), engine at[/FONT]
[FONT="]1000 rpm. (See paragraph 5-11)[/FONT]
[FONT="]If oil pressure is normal, perform step 4.[/FONT]
[FONT="]If oil pressure is high, perform step 5.[/FONT]
[FONT="]Step 4. Check for leaking or damaged detent solenoid.[/FONT]
[FONT="]Tighten detent solenoid if loose and replace if damaged. (See paragraph 5-7)[/FONT]
[FONT="]If detent solenoid is not loose or damaged, clean transmission control valve[/FONT]
[FONT="]assembly. (See paragraph 5-7)[/FONT]
[FONT="]Step 5. Check for loose or damaged vacuum lines and hoses.[/FONT]
[FONT="]Connect vacuum hoses or vacuum lines if loose and replace if damaged. (See[/FONT]
[FONT="]TM 9-2320-289-20)[/FONT]
[FONT="]Step 6. Disconnect vacuum hose from vacuum pump. Install hose and vacuum gage on[/FONT]
[FONT="]vacuum pump. Start engine. Calculate proper vacuum gage reading as shown in[/FONT]
[FONT="]chart. Shut off engine.[/FONT]
[FONT="]If vacuum drops 1 in. Hg or more in less than 1,5 seconds, or if vacuum never[/FONT]
[FONT="]reaches proper gage reading, replace vacuum Dump. (See[/FONT]
[FONT="]TM 9-2320~289-20) [/FONT][FONT="]- -[/FONT]
[FONT="]Step 7.[/FONT]
[FONT="]Remove, clean, and inspect vacuum modulator assembly and modulator valve,[/FONT]