99 sierra shifts rough only in 1st gear and tachometer doesn't work

Asked by Feb 11, 2018 at 09:18 PM about the 1999 GMC Sierra 1500

Question type: Maintenance & Repair

I have a 1999 GMC Sierra. I replaced all the spark
plugs and fuel pump. I left and ignition coil on the
back loose so it was idling rough. I plugged it in
and ever since then I wasn't able to crank it. My
mechanic was able to bypass something by
putting a fuel fuse switch underneath the hood. I
have to turn it on and off accordingly to start the
vehicle. But it's still rides rough in first gear only
and the tachometer does not work at all. Took it to
a dealer and they said the ECM was bad. I already
had a new ECM put in and flashed so I knew that
was incorrect information. And they also said the
transmission was bad. I also knew that was
incorrect information because it only started after i
connected the last ignition coil.  I heard replacing
the ignition switch would solve the issue' but i dobt
want to keep throwong more parts at it..Any help
would be appreciated thank you.

1 Answer

It was the PCM...cleared everything up.

Your Answer:

GMC Sierra 1500 Experts

  • #1
    dragonflyoffshore
    Reputation
    5,660
  • #2
    John Saffrahn
    Reputation
    4,060
  • #3
    Glenn Clingenpeel
    Reputation
    3,860
View All

Related Models For Sale

Used Chevrolet Silverado 1500
1,715 Great Deals out of 153,473 listings starting at $1,295
Used Ford F-150
2,311 Great Deals out of 183,401 listings starting at $1,299
Used Toyota Tundra
487 Great Deals out of 36,930 listings starting at $2,495
Used Chevrolet Silverado 2500HD
330 Great Deals out of 25,053 listings starting at $2,795
Used Dodge Ram 1500
268 Great Deals out of 8,783 listings starting at $1,599
Used Ford F-250 Super Duty
422 Great Deals out of 36,892 listings starting at $2,000
Used Toyota Tacoma
496 Great Deals out of 48,401 listings starting at $2,995
Used Chevrolet Tahoe
551 Great Deals out of 38,129 listings starting at $1,000
Used GMC Yukon
315 Great Deals out of 24,451 listings starting at $1,620
Used Chevrolet Camaro
396 Great Deals out of 27,470 listings starting at $2,100
Used Ford Mustang
415 Great Deals out of 37,442 listings starting at $1,200

Used Cars for Sale

2019 GMC Sierra 1500 For Sale
1,349 listings starting at $47,819
2018 GMC Sierra 1500 For Sale
38 Great Deals out of 28,800 listings starting at $19,490
2017 GMC Sierra 1500 For Sale
125 Great Deals out of 4,904 listings starting at $17,900
2016 GMC Sierra 1500 For Sale
44 Great Deals out of 2,835 listings starting at $15,990
2015 GMC Sierra 1500 For Sale
81 Great Deals out of 4,842 listings starting at $11,990

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.