Question about 1990 GMC Sierra
The first thing you should do is to locate the oil pressure switch/sending unit.
It's a single wire terminal with plastic connect sensor from the engine block.
This oil switch is about $30.
This switch serves two functions.
1) provide oil pressure reading
2) disable the fuel pump relay in event of oil pressure loss.
When this switch is failing to provide the correct pressure to the ECU. The wiring harness can overheat and eventually create a short.
ECM B blow is because the harness is grounding/shorting.
DO NOT drive the truck until you change the oil pressure switch.
After you change the switch,you should spend sometime to inspect the wiring between the fuel pump relay,ECU and fuel pump.
Please post up day on the comment window/page.
I will follow up on it later.
Posted on Aug 03, 2009
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Posted on Jan 02, 2017
Tips for a great answer:
Jan 04, 2015 | 2005 Chevrolet Blazer 4WD
Nov 21, 2011 | Cars & Trucks
Feb 09, 2011 | 1989 Chevrolet C2500
Jan 13, 2011 | 1997 GMC Yukon
Jun 02, 2010 | 1998 Chevrolet Express
May 16, 2010 | Cars & Trucks
445 people viewed this question
Usually answered in minutes!
Step 2: Please assign your manual to a product: