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2003 SL500 , , 2012 E350 4matic wagon
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61 Posts
Discussion Starter #2
Sorry guys I got mouse/button crazy Ok on to the question

I have been trying to figure out how to diagnose the air injection pump. It is not working Pump appears to be Ok - shaft spins freely it is just not engaging and is causing Check engine lite to appear. i have tried to research it with both alldata and the DVDmanual no help on diagnosing or isolating where the problem is. MBZ repair facility says its the computer - didn't say which one. i understand there is a relay for the clutch. Is it possible to replace the relay. I have located what alldata says is the relay but it appears to have other functions There is both a multipin plug and a socket on this "relay" Any advice /help would be appreciated. Thanks
 

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'03 SL500, '03 SL55, '97 SL320, (2) '91 300SL, (2) '91 500SL, '00 S500 -- all for sale
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4,232 Posts
I don't think your engine has a relay. If I am correct, the fuel injection controller directly controls the clutch for the pump (Y33) and the switchover valve (Y32). These two devices are wired in parallel. It would be easiest to check for the correct control voltage (11-14VDC) at Y32. Use Starfinder to locate it.
 

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1996 SL 320
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4 Posts
i have a 96 sl 320...after several cold start checks with the handheld code unit...my check engine light still comes on and my service technician could not find any issue with the air injector or relay(as that was the code determination)...they worked fine at start up...could this be a control unit or wiring harness issue taht is leading to the light to come on??
 
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