Bigyellow Posted January 23, 2016 Share Posted January 23, 2016 Hey guys, new to this whole forum here but here goes nothing! I have a 1996 Mack CL 700 and recently I've been having a problem with it. When I first start the truck and drive a certain distance (seems to be the same distance every time) the electronic malfunction light comes on, and the truck loses a significant amount of power. I know this because I'm usually climbing a steep hill every time this happens, and it seems as tho the turbo loses all its boost. The light will then remain on and the truck will have little power, until it is shut off and left for a few minutes. Then it will reset. Any ideas about what this might be? Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/ Share on other sites More sharing options...
theakerstwo Posted January 23, 2016 Share Posted January 23, 2016 Get some one like mack to read the codes in the ecm.It will tell you what is going on.Other wise you can only guess.It could be low coolant level or losing the VSS signal Then that will derate or shut it down if its programed to do so. 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-321107 Share on other sites More sharing options...
bayouboy Posted January 23, 2016 Share Posted January 23, 2016 When my light was coming on a quick Google search lead me to low coolant level but I never lost power. Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-321111 Share on other sites More sharing options...
Bigyellow Posted January 23, 2016 Author Share Posted January 23, 2016 Yeah I plan on bringing it to Mack, but that's not possible until sometime this coming summer (I live 6 hours from the nearest Mack dealer and I don't use the truck on the highway so). I heard about low coolant but couldn't see that as being the cause for loss of power. I'll look into it tho Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-321170 Share on other sites More sharing options...
theakerstwo Posted January 23, 2016 Share Posted January 23, 2016 Next time it does it see if the cruze will work.If not it may be your VSS bad.Or it could be just the yoke nut on the rear of the trans loose.You can remove the VSS and use a screw driver and stick down in there and see if you can turn the chopper wheel. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-321181 Share on other sites More sharing options...
turckster Posted January 25, 2016 Share Posted January 25, 2016 To find out what the fault is while it is active, push the set/resume switch up until the fault light goes out (cruise switch in the off position). It should flash on/off in two sets. That will help a lot in trying to figure out what is going on here. Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-321461 Share on other sites More sharing options...
Keffer inc Posted January 30, 2016 Share Posted January 30, 2016 I lost my VSS once due to a loose yoke. I don't recall losing power. Does the speedo still work? Check for any codes next time it happens, as turckster said. It will flash a number of flashes, pause for a two seconds, then flash another number of flashes. (Electronic Malfunction Lamp) example, if it flashes once, then pauses two seconds, the flashes seven times, your code is a 1-7, which is related to a coolant sensor issue. Tell us what code you get, we can tell you what it means, or at least where to look. Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-322298 Share on other sites More sharing options...
Keffer inc Posted January 30, 2016 Share Posted January 30, 2016 If this is a morning thing though, I venture to say its a bad coolant sensor and the first owners programmed the truck to shut down as a precaution. Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-322299 Share on other sites More sharing options...
tjc transport Posted January 30, 2016 Share Posted January 30, 2016 To find out what the fault is while it is active, push the set/resume switch up until the fault light goes out (cruise switch in the off position). It should flash on/off in two sets. That will help a lot in trying to figure out what is going on here. ^^^ this^^^with cruise turned off, push the set/resume switch and count the flashes. this will give you the error code, and then you can determine what is wrong. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-322304 Share on other sites More sharing options...
Bulldoggin Posted January 29, 2017 Share Posted January 29, 2017 I have a newer model CXU. The truck ran great without a load on it. The first time I tried pulling a loaded trailer the lightning bolt (MIL) came on and the truck derated and wouldn't go over 10 mph. I drove it straight to the dealer from there which was approx 12-15 miles away. It took me over 2 hours ! That was a painful ride and boy were the people behind me PO'ed ! Lol. Anyways after the dealer checked it out, it was leaking boost air pressure through some bad charge air cooler rubber connector hoses that join the hard pipes. I had a leak in the charge air cooler itself and a leak in the EGR pipe. They replaced everything except the charge air cooler and she pulled like a Mack is supposed to after that, even while still leaking some boost out of the CAC. When you take your CL up a hill, you're putting a load on it and that's when the turbo starts to boost. In my case, the dealer blocked the air intake system and then pressurizes with air to see if it holds or leaks. Mine is an 08, and if mine was worn/cracked, then yours with 12 more years of use and abuse might have a similar issue. I was almost certain my problem was electrical/sensor related. My truck is an autoshift too, so trans is electronically controlled and wouldn't shift passed 4th gear, but ended up being a completely mechanical failure. The one connector had rubbed through on the back side so it looked fine standing and looking at it. The dealer found it by following the air leaks. You could take yours apart and inspect them really good. Good luck buddy Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-360211 Share on other sites More sharing options...
Jcassibry Posted October 27, 2022 Share Posted October 27, 2022 My sequence of lights is 4-3 Quote Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-513741 Share on other sites More sharing options...
tjc transport Posted October 28, 2022 Share Posted October 28, 2022 10 hours ago, Jcassibry said: My sequence of lights is 4-3 auxiliary output #1 voltage high, or low. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment https://www.bigmacktrucks.com/topic/43661-electronic-malfunction/#findComment-513803 Share on other sites More sharing options...
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