My 2003 4x4 Sport needed front drive boot replacement after 120k miles and 8 years of service. After getting the vehicle back from the dealer, the brake booster pump would run for up to 30 seconds in the first minute or so of operation of the truck - every time I turned on the key or started the engine.
Prior to this service I NEVER heard the booster pump run. I have the factory manuals on the truck and checked for possible misalignment of the brackets and suspension items for the booster pump and reservoir. Everything looked OK. I tried flexing the pump assembly around as it was running to see if there was a clearance problem. There was not.
I also checked the computer with a code reader, but no errors were shown.
Finally, I checked the wiring from the wheel speed sensors at each of the front wheels. All appeared to be in order, but I wiggled the connectors a bit to see if they were securely attached.
That fixed the problem! Apparently, one of the connectors was not fully seated and that caused the pump to run on start-up.
Not a very satisfying fix in that I didn't find anything broken, but the problem has not recurred for 2 weeks now.
Hope that helps.
Prior to this service I NEVER heard the booster pump run. I have the factory manuals on the truck and checked for possible misalignment of the brackets and suspension items for the booster pump and reservoir. Everything looked OK. I tried flexing the pump assembly around as it was running to see if there was a clearance problem. There was not.
I also checked the computer with a code reader, but no errors were shown.
Finally, I checked the wiring from the wheel speed sensors at each of the front wheels. All appeared to be in order, but I wiggled the connectors a bit to see if they were securely attached.
That fixed the problem! Apparently, one of the connectors was not fully seated and that caused the pump to run on start-up.
Not a very satisfying fix in that I didn't find anything broken, but the problem has not recurred for 2 weeks now.
Hope that helps.
