Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
07 GMC Acadia abs / traction light comes on above 70 mph(solved ?)
I had a odd one come in yesterday, with 7 pcm codes & 1 abs code for left rear wss code. Test drove with scanner & found left rear wss dropping out at about 70 mph. Checked on lift & found encoder ring on l/r wheel bearing had a couple pieces missing so replaced wheel bearing. After 2nd test drive abs / traction control light came back on but ALL abs wss were reading correct. Checked pcm for codes & code p0101 (maf sensor) was present. So tested maf sensor & couldn't find any fault. After a lot of head scratching decided to look at pcm data while driving & found some erratic readings for map sensor. Sooo, hooked scope to signal wire of map sensor & found it to be bad. Replaced map sensor & cured problem but at no point did i get a code for map sensor. Anyone run into this before ?
Interesting It looks like the PCM was comparing MAF and MAP outputs as a code setting criteria and picking the wrong code to flag up.The MAP sensor self test on key on will probably just to check the engine off baro reading is within limits.
A good reminder to us all that that codes are a symptom not a diagnosis.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Last edit: 7 years 9 months ago by Andy.MacFadyen.
When customer showed up to pickup vehicle they told me the "rest of the story " that was left out in the beginning. They originally took to GM dealer for this issue & was told that there was a tech service bulletin for their problem & a pcm flash would cure everything. Apparently they didn't test anything or visually inspect anything because problems didn't get corrected so one of my customers told them about our shop. Apparently this gm tech just read codes, found a tsb & flashed pcm & never test drove to confirm repair. Not sure why that place has gotten a bad name for their business!
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