Codes

[jjohn]

Help! What does code 87 ( High Ratio Error ) mean ? Thanks John

[Chevylover]

Don't know much more. The only thing i know is :

Transmission code - High gear ratio (4L80-E)
DTC87 - Solenoid-B Stuck Off

So it must be a automatic transmission problem.

Hope this helps a little bit.

Cu,
Sven


JUST FOUND THIS :
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No upshift, stuck in 2nd. After a cold start, some 1994-95 Chevy and GMC C/K-, G- and P-body trucks and some 1996 G- and P-bodies-all equipped with the Hydra-matic 41-SOE automatic-may suffer from no upshift. Engine possibilities are the 4.3-liter V6, 5.7and 7.4-liter gasoline V8s and the 6.5liter turbodiesel V8.

In combination with this, a DTC 87 may set intermittently, causing the PCM to keep the trans in 2nd gear limp-home mode. According to GM, this is all caused by a commanded shift to 3rd or 4th that took longer than 2 seconds at a minimum 25% TPS reading, which set the DTC 87.

If you can't come up with anything during routine diagnostics, the truck will need its EPROM replaced. The new EPROM will have a DTC 87 shift time parameter of 4 seconds (2 seconds longer than before) and a code-enabling temperature of 68F. Note that in 1995, the diesel engines received a change in fuel injection timing pumps that required a new EPROM. The current service pump will work on prior models, so be sure to match the EPROM with the proper fuel injection timing pump on the diesels.

To get the new EPROM, it looks like you'll need the broadcast code and scan ID of the old one. There are some 80 different chips to cover all the applications.
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[jjohn]

Thanks for the info, now next question. Is the EPROM the chip on top of the ECM? If not where is it ? Thanks John

[Chevylover]

Thanks for the info, now next question. Is the EPROM the chip on top of the ECM? If not where is it ? Thanks John

Until 1995 there are two eproms. One in the ECM (engine control modul) and one TCM (transmission control modul) for the tranny. Later there was a PCM the controlled the engine AND the tranny. I don't know exactly where it is, but i think i should be nearby the tranny.

Anyone there who knows better ?


Cu,
Sven