Diesel Bombers SIGN UP NOW

National Association of Diesel Motorsports
Go Back   Diesel Bombers > Tech Talk > Chevrolet / GMC Diesel Tech Articles
Sign in using an external account
Register Forgot Password?
Search
Welcome to Diesel Bombers


Registered Members don't see these ads. Register now it's free!

Chevrolet / GMC Diesel Tech Articles All years Duramax

 
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 01-30-2011, 09:27 PM
FormerVendor
Status: 1-888-200-4708

  award
Default How to: Replace NSBU Switch.

NSBU: "Neutral Start Back Up" switch. AKA PNP ("Park Neutral Position") switch.


Location: The switch is located on driver's side of the Allison transmission.

Symptoms of a bad NSBU switch
- No Start condition.
- Sets DIC codes MAY suggest the NSBU as the cause: P0700, P0708, P0847, P0872, P0875, P1711 and P1713.
- PRNDL display may not show up or flash.
- Delayed or No Engagement of the transmission.
- SEL (service engine light) message that reads something like "shift range inhibited".

There are 2 switches for the 5 Speed Allison Transmissions:
- 2001-2004 Allison NSBU Switch (LB7). Part no. 29540479. Has 2 electrical connectors.
- 2004-2005 Allison NSBU Switch (LLY). Part no. 29541852. Has 1 electrical connector.

Tools Needed:
13mm Deep 6 pt 3/8 drive socket
15mm Wrench
6 inch extension
3/8" ratchet
Small file (Optional)

Here's what I used


The new switch has a thin metal clip called a Neutral Assurance Bracket to ensure that the NSBU remains in the neutral position. DO NOT REMOVE UNTIL THE NEW SWITCH HAS BEEN INSTALLED.

1. Make sure you block the wheels and set the parking brake.

2. Put the transmission in neutral.

3. Disconnect NSBU wiring harness. This one has one connector. LB7s 2001-2004 have 2 plugs. Locate the retainer (blue) and pull it out. Now gently pry the lock up. Wiggle as you pry helps removal.




4. Disconnect the shift linkage/cable from the shift lever at the transmission. With a wrench hold the shifter from rotating out of neutral. Remove the nut from the end of the selector shaft. Carefully remove the selector lever from the selector shaft.


5. Remove the 2 bolts that attach the NSBU switch (the front driveshaft will get in the way a bit but you should be able to access the bolt with the socket) and pull off the old NSBU switch. There'll be some resistance when you pull it off.


6. If for some reason the transmission is not in neutral, use a wrench on the selector shaft flats and rotates the shaft to its furthest clockwise position and then rotates counter-clockwise two detents. Or align the flats with the “N” on the transmission.


7. Take a file and touch up the selector shaft at the end near the flats...there may be some burrs that could create some slop if the new NSBU switch is slid over the shaft without filing.

8. Slide the new NSBU switch over the selector shaft. The metal clip (neutral assurance bracket) on the switch helps to ensure the switch is properly aligned to the shaft. The bolts holding the NSBU to transmission should be tightened to 18-21 lb ft. Now it's ok to remove the metal clip from the NSBU housing.

9. Slide the grey splash shield onto the NSBU switch so that it fits securely against the switch. Do this BEFORE re-installing the shift lever.

10. Re-install the shift level. Again use an adjustable wrench on the shift lever while tightening the nut on the end of the selector shaft. OEM specs for the nut is 15-20 lb ft.

11. Connect the wiring harness back onto the NSBU switch.

12. Clear the all DTCs and your ready to go.
[/FONT]
 
 
 
 


Thread Tools Search this Thread
Search this Thread:

Advanced Search


 
All times are GMT -5. The time now is 01:04 PM.

Copyright And Legal Notice Links Of Interest

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.5.2
Diesel Bombers ® - All Content Protected Under Intellectual Property Rights Law of Registered Trademarks
Reg. No. 3,494,401 Cls. 100, 101 & 104 Under Int. Cl. 38
USE AT YOUR OWN RISK WE HOLD NO LIABILITY FOR ANY CONTENT RIGHT, WRONG OR INDIFFERENT

Protected by Copyscape Duplicate Content Check


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233