Crakker Posted November 8, 2021 Share Posted November 8, 2021 Have a 2009 trident with mp8 having trouble with starting, The starter was replaced just before purchase, can here relay clicking when I turn the key and starter solenoid clicking also but may take multiple times before the starter turns motor over is very inconsistent with how many times it takes before it actually turns over Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-482590 Share on other sites More sharing options...
Orlando Fossi Posted February 24, 2022 Share Posted February 24, 2022 On 1/24/2018 at 10:19 PM, turckster said: All Mack mp engine starters are controlled by the engine ecu. The eecu provides the ground circuit for the starter relay. The purpose for that is to protect the starter from overcranking/overheating. If the eecu sees excessive crank time it shuts off the ground circuit to the starter relay for a minimum of 30 seconds. Hi, I’m Orlando I have a Mack semi truck 2008 with a MP8 I left the switch open the whole night in the morning I replaced the batteries and now it don’t want start checking I found that I have +12v on the starter solenoid when put switch on the start position but I don’t have ground do you know what could be? Thanks 👍🏽 Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-490195 Share on other sites More sharing options...
Mackpro Posted February 24, 2022 Share Posted February 24, 2022 (edited) With any MP engine that won’t crank , check and see if you can view the engine hours in the dash cluster . If you have the high end dash cluster with the stalk switch , you can view it under Trip Info. If all you see for engine hours is dashes then the engine ECM is bad or not powering up . Edited February 24, 2022 by Mackpro 1 Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-490206 Share on other sites More sharing options...
Onyx610 Posted February 24, 2022 Share Posted February 24, 2022 8 minutes ago, Mackpro said: With any MP engine that won’t crank , check and see if you can view the engine hours in the dash cluster . If you have the high end dash cluster with the stalk switch , you can view it under Trip Info. If all you see for engine hours is dashes then the engine ECM is bad or now powering up . Did not know that….thanks Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-490207 Share on other sites More sharing options...
Mackpro Posted February 24, 2022 Share Posted February 24, 2022 (edited) As one of the other posters said earlier in this thread , the engine ECM grounds the starter relay that’s bolted to the starter. The vehicle control unit (VECU ) / key switch might send power to the starter relay but the final decision is made by the engine ECM to ground and engage the starter Edited February 24, 2022 by Mackpro 1 Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-490211 Share on other sites More sharing options...
dgk1 Posted April 6, 2022 Share Posted April 6, 2022 I have a 2011 cxu. Truck was running when driver went in store. Came back out had cut off. No power at all with key switch on. Checked fuses, battery connection all look good. Any suggestions on what to look at next Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-494580 Share on other sites More sharing options...
Onyx610 Posted April 7, 2022 Share Posted April 7, 2022 By any chance does this truck have a master switch on it? Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-494657 Share on other sites More sharing options...
Joey Mack Posted April 7, 2022 Share Posted April 7, 2022 did you check the fusable link in the battery box? I believe it has one.. it is a short wire that is not very thick, it is a ground, bolted to the frame.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-494668 Share on other sites More sharing options...
Elijah Posted April 10, 2022 Share Posted April 10, 2022 On 1/30/2019 at 10:25 AM, George h said: I have a 2009 Mack with a mp-8 . You turn on the key and crank the starter will engaged for about a second or less then it shuts off you can cycle the key and it will do it again it has a new wire harness new starter all the fuses and relays have been replaced the dealership is worked on this problem 4 different times and have not fixed it my question is it possible that the engine ecm is bad or the eecm I don't want to replace the wrong one Did you ever come across a solution?have the same problem in our truck but it’s 1 year old and could have been switched sensors. Battery and alternator test good. Any ideas? Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-494897 Share on other sites More sharing options...
Elijah Posted April 10, 2022 Share Posted April 10, 2022 On 1/30/2019 at 10:04 PM, turckster said: Sounds like the cam position and crank position sensor connectors are crossed. The ecu see's excessive speed and shuts off the starter. Ever find a solution? Came across the same problem yesterday. Can’t be switched sensors and we tested the battery’s and alternator. Can’t be switched sensors due to a brand new truck and has never been worked on before problem occurred. Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-494898 Share on other sites More sharing options...
wishiknu Posted January 12 Share Posted January 12 I have a 2013 GU713 that won't start. Yesterday evening on the way in one of our drivers sent me a pic of the dash saying ALERT: DPF system fault. DPF System Service Required. And this morning the truck wouldn't start at all. Nothing to starter. When I checked the starter relay that's bolted to the starter. The ground side was reading start signal. So what ever is supposed to be grounding it, isn't. I'm assuming it's the ECM but I don't know anyway to confirm that. Someone did tell me about checking total engine hours and if it's just dashes it means the ecm is bad. Well, it's just dashes. But how can I confirm that before I spend the $ on an ecm? Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-545018 Share on other sites More sharing options...
Muna Posted May 26 Share Posted May 26 2019 Mack won’t start has no crack sound when turning the key. Power inside truck but it won’t start. Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-552596 Share on other sites More sharing options...
Joey Mack Posted May 27 Share Posted May 27 let me guess.... its deleted? Quote Link to comment https://www.bigmacktrucks.com/topic/52270-mp8-engine-no-crank-with-key-switch/page/2/#findComment-552602 Share on other sites More sharing options...
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