festus59 Posted April 1, 2011 Share Posted April 1, 2011 I have a 1998 RD688S with an E7400, It wouldn't start, unhook the battery for five minutes then it starts. Now after changing the oil, I started it let the oil pressure build up then it shuts down, has not started since, unhooked battery, no help. I have had a new oil pressure sensor put on (the one on the top of the oil filter) before all this happened. I'm not a mechanic but wonder if these are common problems are not. I do know it is somewhat computerized because I had the top speed increased at a Mack dealer. They are too far away and I'm trying to avoid a big towing bill. Thanks.....Festus Quote Link to comment https://www.bigmacktrucks.com/topic/18548-1998-rd688s/ Share on other sites More sharing options...
fjh Posted April 1, 2011 Share Posted April 1, 2011 I have a 1998 RD688S with an E7400, It wouldn't start, unhook the battery for five minutes then it starts. Now after changing the oil, I started it let the oil pressure build up then it shuts down, has not started since, unhooked battery, no help. I have had a new oil pressure sensor put on (the one on the top of the oil filter) before all this happened. I'm not a mechanic but wonder if these are common problems are not. I do know it is somewhat computerized because I had the top speed increased at a Mack dealer. They are too far away and I'm trying to avoid a big towing bill. Thanks.....Festusdoes it crank at all? When you turn the key on does the dash lite up if not then you likely have a bad relay the accessory relay/s are generally mounted beneath the ashtray panel on top of the middle dash. Or depending on year inside the glove box panel to the left side.Also if you have had lots of rain in your area look behind the passenger kick panel ( 4 screws) look for a smaller looking black box (Vehicle ECU) I have seen leaky windshields cause these to fail unplug the box and check the plug for green connections just some stuff to look for! Good luck Quote Link to comment https://www.bigmacktrucks.com/topic/18548-1998-rd688s/#findComment-75279 Share on other sites More sharing options...
festus59 Posted April 4, 2011 Author Share Posted April 4, 2011 does it crank at all? When you turn the key on does the dash lite up if not then you likely have a bad relay the accessory relay/s are generally mounted beneath the ashtray panel on top of the middle dash. Or depending on year inside the glove box panel to the left side.Also if you have had lots of rain in your area look behind the passenger kick panel ( 4 screws) look for a smaller looking black box (Vehicle ECU) I have seen leaky windshields cause these to fail unplug the box and check the plug for green connections just some stuff to look for! Good luckYes it does crank, lights to lite up. I will check the connection on the ECU. Thanks....I'll get back to you Quote Link to comment https://www.bigmacktrucks.com/topic/18548-1998-rd688s/#findComment-75498 Share on other sites More sharing options...
cgallamore Posted April 4, 2011 Share Posted April 4, 2011 hey festus, do you live in festus,mo.???????????? Quote http://www.bigmacktrucks.com/uploads/1272400769/gallery_4852_794_314995.jpg Link to comment https://www.bigmacktrucks.com/topic/18548-1998-rd688s/#findComment-75505 Share on other sites More sharing options...
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