{"id":1201,"date":"2018-08-01T16:50:36","date_gmt":"2018-08-01T20:50:36","guid":{"rendered":"https:\/\/www.fs1inc.com\/blog\/?p=1201"},"modified":"2025-12-04T00:06:58","modified_gmt":"2025-12-04T05:06:58","slug":"1999-jeep-grand-cherokee-4-0l-pcm-ecm-ecu-control-module-engine-computer-replacement","status":"publish","type":"post","link":"https:\/\/www.fs1inc.com\/blog\/1999-jeep-grand-cherokee-4-0l-pcm-ecm-ecu-control-module-engine-computer-replacement\/","title":{"rendered":"1999 Jeep Grand Cherokee 4.0L &#8211; PCM ECM ECU Control Module (Engine Computer) Replacement"},"content":{"rendered":"<p>The Powertrain Control Module, or PCM, is a pre-programmed digital computer that operates the engine control system of a vehicle. People refer to it as JTEC sometimes. As the input data changes, the PCM adjusts its response to the various output devices it operates.\u00a0 If the PCM, the \u201cbrains\u201d, fails to work correctly, the rest of the engine will have issues as well. Luckily, if proper diagnosis points toward replacement of the PCM as the solution, the PCM can be easily replaced to fix the issue. We\u2019ll show you how to replace a PCM ECM ECU Module on a 1999 Jeep Grand Cherokee.<\/p>\n<p>Begin replacing the PCM of your 1999 Jeep Grand Cherokee by locating the module. A TCM, Transmission Control Module, might be equipped in that area and will need to be removed to replace the PCM. The coolant reserve\/overflow tank will be in the way but the location of the PCM is on the cowl panel in the right\/rear side of the engine compartment.<\/p>\n<p><a href=\"https:\/\/www.fs1inc.com\/\"><img fetchpriority=\"high\" decoding=\"async\" class=\"aligncenter wp-image-16656 size-medium\" src=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2019\/08\/symptoms-when-pcm-goes-bad-or-fails-500x235.png\" alt=\"Shop at flagship one inc for engine control module\" width=\"600\" height=\"235\" \/><\/a><\/p>\n<h4><strong>REMOVAL<\/strong><\/h4>\n<p>1- Disconnect negative battery cable from the battery.<\/p>\n<p>2- If equipped, remove the Transmission Control Module (TCM).<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-1184 size-medium\" title=\"1999 Jeep Grand Cherokee Replacement 2\" src=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2004jeepgrandcherokee1-347x365.jpg\" alt=\"1999 Jeep Grand Cherokee Replacement 2\" width=\"347\" height=\"365\" srcset=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2004jeepgrandcherokee1-347x365.jpg 347w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2004jeepgrandcherokee1.jpg 433w\" sizes=\"(max-width: 347px) 100vw, 347px\" \/><\/p>\n<p>3- Remove the coolant reserve\/overflow tank.<\/p>\n<p>4- Remove cover over the electrical connectors. Cover snaps onto the PCM.<\/p>\n<p>5- Carefully unplug the three 32\u2013way connectors from the PCM.<\/p>\n<p>6- Remove the three PCM bracket-to-body mounting nuts.<\/p>\n<p>7- Remove the PCM\/PCM bracket assembly itself from the vehicle.<\/p>\n<p>8- Remove the 3 PCM-to-PCM bracket bolts (screws).<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-1186 size-medium\" title=\"1999 Jeep Grand Cherokee Replacement 3\" src=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2004-jeep-grand-cherokee-pcm-ecm-replacement-guide-3-427x365.jpg\" alt=\"1999 Jeep Grand Cherokee Replacement 3\" width=\"427\" height=\"365\" srcset=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2004-jeep-grand-cherokee-pcm-ecm-replacement-guide-3-427x365.jpg 427w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2004-jeep-grand-cherokee-pcm-ecm-replacement-guide-3.jpg 450w\" sizes=\"(max-width: 427px) 100vw, 427px\" \/><\/p>\n<h4><strong>REPLACEMENT<\/strong><\/h4>\n<p>1- Check for damaged pins in the three 32\u2013way electrical connectors. If pins not damaged, continue.<\/p>\n<p>2- Install PCM to its mounting bracket. Tighten the three mounting bolts to 3 N\u00b7m (25 in. lbs.) torque.<\/p>\n<p>3- Install PCM\/PCM bracket to the body. Install the 3 nuts and tighten to 9 N\u00b7m (80 in. lbs.) torque.<\/p>\n<p>4- Install the three 32\u2013way connectors.<\/p>\n<p>5- Install cover over the electrical connectors. Cover snaps onto the PCM.<\/p>\n<p>6- Install the coolant reserve\/overflow tank.<\/p>\n<p>7- Reinstall the Transmission Control Module (TCM), if needed.<\/p>\n<p>8- Reconnect the negative battery cable back to the battery.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-1151 size-medium\" title=\"1999 Jeep Grand Cherokee Replacement 4\" src=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement-365x365.jpg\" alt=\"1999 Jeep Grand Cherokee Replacement 4\" width=\"365\" height=\"365\" srcset=\"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement-365x365.jpg 365w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement-480x480.jpg 480w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement-120x120.jpg 120w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement-360x360.jpg 360w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement-580x580.jpg 580w, https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2018\/07\/2002-jeep-liberty-3-7-L-pcm-ecm-replacement.jpg 600w\" sizes=\"(max-width: 365px) 100vw, 365px\" \/><\/p>\n<p>We have a huge selection of Programmed 1999 Jeep Grand Cherokee PCMs if a replacement PCM is needed. The PCM you order with us is 100% ready for immediate installation. If you have any questions, please don\u2019t hesitate to call our Customer Service department at\u00a0<strong>516-766-2223<\/strong>, we\u2019re always here to help!<\/p>\n<p><a href=\"https:\/\/www.fs1inc.com\/1999-jeep-grand-cherokee-4-0l-engine-computer-pcm-ecm-ecu-programmed.html\">1999 Jeep Grand Cherokee 4.0L<\/a><\/p>\n<p>Flagship One, Inc. brings the best service at the lowest prices.<\/p>\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A step by step guide to locating and replacing a 1999 Jeep Grand Cherokee 4.0L Engine Computer.<\/p>\n","protected":false},"author":1,"featured_media":1185,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5,34,40],"tags":[52,47,23,22,46,45,42,29,43],"class_list":["post-1201","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-feature","category-jeep","category-repair-manuals","tag-52","tag-cherokee","tag-ecm","tag-ecu","tag-grand","tag-jeep","tag-module","tag-pcm","tag-replace"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>1999 Jeep Grand Cherokee 4.0L - PCM ECM ECU Control Module (Engine Computer) Replacement - Flagship One Blog<\/title>\n<meta name=\"description\" content=\"PCM failed? 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OEM Engine Computers  Control Modules","publisher":{"@id":"https:\/\/www.fs1inc.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.fs1inc.com\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.fs1inc.com\/blog\/#organization","name":"Flagship One, Inc.","url":"https:\/\/www.fs1inc.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.fs1inc.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2019\/06\/web-lg-fs1-logo.png","contentUrl":"https:\/\/www.fs1inc.com\/blog\/wp-content\/uploads\/2019\/06\/web-lg-fs1-logo.png","width":1341,"height":1098,"caption":"Flagship One, Inc."},"image":{"@id":"https:\/\/www.fs1inc.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/flagshipone","https:\/\/x.com\/theflagshipone","https:\/\/www.instagram.com\/flagship_one","https:\/\/www.youtube.com\/channel\/UC0oyKphffBM2qkJ-gKPmMXw"]},{"@type":"Person","@id":"https:\/\/www.fs1inc.com\/blog\/#\/schema\/person\/a3cf463514bd03eb7656953ef8f75700","name":"FlagshipOne","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/secure.gravatar.com\/avatar\/351b81e51993825aea73280c48061a7205fdd2189730ebbdee5d63894c5cebb4?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/351b81e51993825aea73280c48061a7205fdd2189730ebbdee5d63894c5cebb4?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/351b81e51993825aea73280c48061a7205fdd2189730ebbdee5d63894c5cebb4?s=96&d=mm&r=g","caption":"FlagshipOne"},"description":"The world's top supplier of programmed OEM (Original Equipment Manufacturer) Powertrain Control Modules (PCM), Engine Control Modules (ECM), Injection Control Modules (IDM), Body Control Modules (BCM), Transmission Control Modules (TCM), Engine Control Units and all other car control units. 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