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Discussion Starter · #1 ·
Backstory - i have a 05 s40 t5 that had a busted flexpipe for about a year, recently replaced with oem. Finally was excited to get a car that runs normal again. Car is quiet now but the fuse 33 keeps blowing and when it does, the car is SUPER sputtery under throttle. All O2 sensors are new, so im assuming its gotta be the vacuum pump? If so, is it unsafe to disconnect the vacuum pump to drive the car? Trying to diagnose to see IF its the problem. Help!!
 

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2007 Volvo V50 T5 AWD M66
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Fuse 33 is for your O2 sensor heaters. *Edit* I guess some years also put the vacuum pump on that fuse. The vacuum pump doesn't do much besides the brake booster I can't see why starting it without it plugged in would do damage. I wouldn't be driving far though.
 

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I've seen a few shorted vacuum switches cause the pumps to constantly run and eventually overheat, seize and blow the fuse.
 

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Discussion Starter · #4 ·
Would be fixed by simply replacing the pump? And do you think driving with the pump disconnected would be a bad idea? Like i said, just for diagnosing.
 

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If it was caused by a shorted switch, you'll need to replace the switch as well.

You can test the pump by supplying it with direct power and ground and seeing if it works.
 

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Backstory - i have a 05 s40 t5 that had a busted flexpipe for about a year, recently replaced with oem. Finally was excited to get a car that runs normal again. Car is quiet now but the fuse 33 keeps blowing and when it does, the car is SUPER sputtery under throttle. All O2 sensors are new, so im assuming its gotta be the vacuum pump? If so, is it unsafe to disconnect the vacuum pump to drive the car? Trying to diagnose to see IF its the problem. Help!!
"replaced with OEM" means whole downpipe with CAT and all new sensors? Were the lambda sensors also OEM/came with DP or are new but aftermarket?
 

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Discussion Starter · #7 · (Edited)
The entire downpipe and o2 sensors And wires came directly off a parts car. (The pipe was functioning fine). Can someone direct me towards the vacuum pump “switch”? Should i replace both the pump and switch to be safe? Is it a known issue with these cars?
 

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Discussion Starter · #9 ·
Today i am going to disconnect the pump and see if it blows the fuse. Is this a case of process of elimination but unplugging and testing unplugging and testing? I really dont think its the o2..
 

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It's not likely the O2.

Like I said, I test the pump to see if its seized. If it is, I'll leave it disconnected and measure voltage to the pump (from the switch). I'll put a new fuse in and check to see if the switch switches off when it should or if it is shorted. It usually is, and I sell a pump and switch.
 

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Discussion Starter · #11 ·
It's not likely the O2.

Like I said, I test the pump to see if its seized. If it is, I'll leave it disconnected and measure voltage to the pump (from the switch). I'll put a new fuse in and check to see if the switch switches off when it should or if it is shorted. It usually is, and I sell a pump and switch.
How much for pump and switch? Link?
 

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Discussion Starter · #12 ·
Update - bought a new pump, installed, car is driving good, no blown fuse, but the check engine light did come back. Going to get it scanned. Ps - i have NO idea where the switch is on an 05 awd t5?! Is it built into the vacuum pump?

Im hoping its just an issue where the code needs to be cleared because i was trying to reset the code by disconnecting the battery.

Will update on code later today.
 

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If the pump is not running constantly, the switch isn't shorted.

The switch is not built into the pump. It is in the hose going to the booster, as I stated above. It's basically behind the battery.
 

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Discussion Starter · #14 ·
Gotcha. Was wondering why I couldn't find the switch. So if it isnt the pump, and the 02 sensors are new...and because the pump switch is most likely not shorted...do you suspect it just is a case where the code is just needing to be cleared? Like i said, car is driving fine now.
 
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