{"id":22742,"date":"2025-03-27T08:31:41","date_gmt":"2025-03-27T08:31:41","guid":{"rendered":"https:\/\/www.obd2tool.com\/blog\/?p=22742"},"modified":"2025-03-26T08:46:47","modified_gmt":"2025-03-26T08:46:47","slug":"how-to-resolve-allison-3000-4000-gen5-transmission-p071a-neutral-at-stop-input-failed-on","status":"publish","type":"post","link":"https:\/\/www.obd2tool.com\/blog\/how-to-resolve-allison-3000-4000-gen5-transmission-p071a-neutral-at-stop-input-failed-on\/","title":{"rendered":"How to Resolve Allison 3000 &#038; 4000 Gen5 Transmission P071A Neutral at Stop Input Failed ON"},"content":{"rendered":"<p>This guide provides step-by-step instructions on diagnosing and resolving the P071A Neutral at Stop Input Failed ON issue in Allison 3000 &amp; 4000 Gen5 transmissions.<\/p>\n<h3>Related Contents:<\/h3>\n<p><a href=\"https:\/\/www.obd2tool.com\/blog\/allison-doc-transmission-diagnostic-software-free-download\/\">2025 2019 Allison DOC Transmission Diagnostic Software Free Download<\/a><br \/>\n<a href=\"https:\/\/www.obd2tool.com\/goods-10653-NEXIQ-3-USB-Link-Software-Diesel-Truck-Diagnostic-Tool.html\">NEXIQ USB Link 3<\/a><br \/>\n<a href=\"https:\/\/www.obd2tool.com\/goods-10776-Allison-DOC-Premium-Diagnostic-Software.html\">Allison DOC Premium Diagnostic Software<\/a><\/p>\n<h2>Understanding the Neutral at Stop Function<\/h2>\n<h3>Circuit Description<\/h3>\n<p>When the Neutral at Stop function is active, the Transmission Control Module (TCM) automatically shifts the transmission to a reduced load state similar to Neutral (N) when the vehicle is stopped. This feature:<\/p>\n<ul>\n<li>Improves fuel efficiency<\/li>\n<li>Reduces heat buildup during frequent stop\/start operations<\/li>\n<\/ul>\n<p>For activation, the following conditions must be met:<\/p>\n<ul>\n<li>Vehicle in first range<\/li>\n<li>Vehicle completely stopped<\/li>\n<li>Service brakes applied<\/li>\n<li>Accelerator pedal at 0%<\/li>\n<li>TCM GPI terminal for Neutral at Stop detects V+, V Ign, or V Bat<\/li>\n<\/ul>\n<h3>Deactivation Conditions<\/h3>\n<p>Neutral at Stop disengages when the service brake is released. Additional controls, such as a door switch or dashboard switch, may also be used in series with the service brake pressure switch.<\/p>\n<p>The input signal to activate Neutral at Stop may be located on W102, W123, or W143, depending on the I\/O package selected in the TCM calibration. This function typically uses a switch-to-battery input (analog).<\/p>\n<p>For further details, refer to the OEM Technician\u2019s Library.<\/p>\n<h2>Neutral at Stop Wiring Details<\/h2>\n<table>\n<thead>\n<tr>\n<th>GPI #<\/th>\n<th>GPI Type<\/th>\n<th>TCM Pin<\/th>\n<th>Wire #<\/th>\n<th>Wire Color<\/th>\n<th>Termination Point<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>1<\/td>\n<td>+<\/td>\n<td>23<\/td>\n<td>123<\/td>\n<td>Green<\/td>\n<td>Service Brake Pressure Switch to V+ or PLC Output<\/td>\n<\/tr>\n<tr>\n<td>2<\/td>\n<td>+<\/td>\n<td>2<\/td>\n<td>102<\/td>\n<td>Yellow<\/td>\n<td>Service Brake Pressure Switch to V+ or PLC Output<\/td>\n<\/tr>\n<tr>\n<td>3<\/td>\n<td>+<\/td>\n<td>43<\/td>\n<td>143<\/td>\n<td>Blue<\/td>\n<td>Service Brake Pressure Switch to V+ or PLC Output<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>What Happens When DTC P071A Sets?<\/h2>\n<p>When DTC P071A is active, the following occurs:<\/p>\n<ol>\n<li>The DTC is stored in the TCM history.<\/li>\n<li>The CHECK TRANS light does not illuminate.<\/li>\n<li>TCM disables the Neutral at Stop function.<\/li>\n<\/ol>\n<h2>How to Clear the DTC \/ CHECK TRANS Light<\/h2>\n<ul>\n<li>Use a diagnostic tool to clear the DTC from the TCM history.<\/li>\n<li>The TCM will automatically clear the DTC after 40 successful warm-up cycles without the issue recurring.<\/li>\n<\/ul>\n<h2>Diagnostic Aids: Common Causes of P071A<\/h2>\n<h3>1. Electrical Short or Wiring Issues<\/h3>\n<ul>\n<li>Short to power or short to another wire in the Neutral at Stop GPI circuit (W102, W123, or W143).<\/li>\n<\/ul>\n<h3>2. Service Brake Integration Issues<\/h3>\n<ul>\n<li>Defective brake switch or incorrect wiring (e.g., pressure switches staying closed when they should be open).<\/li>\n<li>If additional switches (e.g., Neutral at Stop enable switch or door switch) are wired in series, they may be stuck closed or miswired.<\/li>\n<\/ul>\n<h3>3. PLC (Programmable Logic Controller) Integration Issues<\/h3>\n<ul>\n<li>Incorrect wiring, programming, or faulty circuit in the PLC controlling the TCM GPI signal.<\/li>\n<li>If the PLC maintains the circuit above 3.4 volts when the service brakes are released, the issue may persist.<\/li>\n<\/ul>\n<h3>4. TCM Programming Errors<\/h3>\n<ul>\n<li>Neutral at Stop function may have been incorrectly enabled in the TCM settings.<\/li>\n<\/ul>\n<h3>5. Voltage Potential Differences<\/h3>\n<ul>\n<li>TCM ground voltage differs from the OEM voltage source responsible for switching the GPI circuit (e.g., PLC, vehicle ignition, body controller).<\/li>\n<\/ul>\n<h3>6. Defective TCM<\/h3>\n<ul>\n<li>If all other diagnostics check out, the TCM itself may be faulty.<\/li>\n<\/ul>\n<p>By following this guide, you can diagnose and fix the P071A issue to restore the Neutral at Stop functionality in Allison 3000 &amp; 4000 Gen5 transmissions.<\/p>\n<p>More Allison repair case,please refer to <a href=\"https:\/\/www.obd2tool.com\/blog\/category\/allison-trouble-repair\/\"><u>Allison Trouble Repair<\/u><\/a><\/p>\n<!-- AddThis Advanced Settings generic via filter on the_content --><!-- AddThis Share Buttons generic via filter on the_content -->","protected":false},"excerpt":{"rendered":"<p>This guide provides step-by-step instructions on diagnosing and resolving the P071A Neutral at Stop Input Failed ON issue in Allison<!-- AddThis Advanced Settings generic via filter on get_the_excerpt --><!-- AddThis Share Buttons generic via filter on get_the_excerpt --><\/p>\n","protected":false},"author":1,"featured_media":22746,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3772,65],"tags":[3792,3791,3793,3790,3544],"views":2778,"_links":{"self":[{"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/posts\/22742"}],"collection":[{"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/comments?post=22742"}],"version-history":[{"count":1,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/posts\/22742\/revisions"}],"predecessor-version":[{"id":22747,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/posts\/22742\/revisions\/22747"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/media\/22746"}],"wp:attachment":[{"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/media?parent=22742"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/categories?post=22742"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.obd2tool.com\/blog\/wp-json\/wp\/v2\/tags?post=22742"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}