vtm light code 77 with no cel troubleshooting
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Honda-Tech Member
Joined: Jun 2005
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From: Elyria, OH, US
vtm light code 77 with no cel troubleshooting
so ive had a vtm light on my 03 pilot for probably 6 months now and im finally sick of looking at it. i dont have any cels, but had one in the past that disappeared and hasnt came back. the vtm code is 77 which is usually related to egr valve or something of the sort from what ive read, but in that case a cel is usually also present. the pilot has 208k. i just cleaned out the egr ports in the intake but havent replaced the egr yet. anyone have input before i start blindly replacing things? ive only had the vehicle for 30k and it was a one owner, dealership maintained vehicle prior.
the vtm light will come on as soon as i drive a few feet and is constant. if i reset it, it comes on immediately as soon as the vehicle is put in drive and moves under its own power.
i noticed over the summer the car would idle low sometimes and almost die, but the alternator locked up shortly thereafter so im blaming it on that. idle otherwise seems to be regular w/ no rpm fluctuations that ive noticed.
the vtm light will come on as soon as i drive a few feet and is constant. if i reset it, it comes on immediately as soon as the vehicle is put in drive and moves under its own power.
i noticed over the summer the car would idle low sometimes and almost die, but the alternator locked up shortly thereafter so im blaming it on that. idle otherwise seems to be regular w/ no rpm fluctuations that ive noticed.
Honda-Tech Member
Joined: Aug 2004
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From: Washington Dc
Re: vtm light code 77 with no cel troubleshooting
Before cleaning up the egr port you should have tested if the egr valve or the egr port , to do the test simply iddle the engine and unplug the egr , find a way to provide ground and power to the egr valve ( at the deler we do it with pigtail connectors from spare wire harness ) apply 12 v from battery to egr valve if you can hear a click on the egr and the truck doesnt stall then u have a clogg port ,if the truck stalls egr system is good , or if you dont heard a click at all when 12 v is applied the your egr is the problem
Honda-Tech Member
Joined: Aug 2004
Posts: 2,379
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From: Washington Dc
Re: vtm light code 77 with no cel troubleshooting
THIS IS HOW HONDA WANT YOU TO DIAGNOSE A CODE 77-1
DTC 77: PCM
Check the PCM for DTCs. Repair the cause for the PCM DTCs before troubleshooting DTC 77.
Clear the DTC.
Test-drive the vehicle, and watch the VTM-4 indicator.
Does the VTM-4 indicator come on? YES - Go to step 3.
NO - The system is OK at this time.n
Replace the PCM. Test-drive the vehicle, and watch the VTM-4 indicator.
Does the VTM-4 indicator come on? YES - Check for loose terminal fit in the VTM-4 control unit. If it is normal, replace the VTM-4 control unit.n
NO - The system is OK at this time.n
DTC 77: PCM
Check the PCM for DTCs. Repair the cause for the PCM DTCs before troubleshooting DTC 77.
Clear the DTC.
Test-drive the vehicle, and watch the VTM-4 indicator.
Does the VTM-4 indicator come on? YES - Go to step 3.
NO - The system is OK at this time.n
Replace the PCM. Test-drive the vehicle, and watch the VTM-4 indicator.
Does the VTM-4 indicator come on? YES - Check for loose terminal fit in the VTM-4 control unit. If it is normal, replace the VTM-4 control unit.n
NO - The system is OK at this time.n
Technical Hero
Joined: May 2002
Posts: 9,875
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From: Charlotte, NC, 28227
Re: vtm light code 77 with no cel troubleshooting
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