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1986 240 DL IAC

Help, Advice, Owners' Discussion and DIY Tutorials on all Volvo's "mid era" rear wheel drive Volvos.

1975 - 1993 240
1983 - 1992 740
1982 - 1991 760
1986 - 1991 780
1990 - 1998 940
1990 - 1998 960
1997 - 1998 V90/S90

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jimmy57
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Re: 1986 240 DL IAC

Post by jimmy57 »

One power wire and two grounding wires. One grd is open pulse and the other is closed pulse. If the closed pulse is missing then the valve goes full or near full open. Go to RH kick panel insie forward of door opening and locate the LH ECU and then unplug it and spray the connectins with WD-40 and then plug it in and unplug it 3-4 times and then crank engine and see if the idle is normal speed.

ECT sensor issues cause high idle and throttle switch issues do too.

mhgreen
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Year and Model: 240 DL 1986
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Post by mhgreen »

Bad ecu. Plugged in a good one (borrowed) and idle was fine
“Some cannot loosen their own chains and can nonetheless redeem their friends.”

mhgreen
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Year and Model: 240 DL 1986
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Post by mhgreen »

Cleaning ecu connection as discussed above - worth trying? Or is bad, bad?
“Some cannot loosen their own chains and can nonetheless redeem their friends.”

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93Regina
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Post by 93Regina »

mhgreen wrote:Cleaning ecu connection as discussed above - worth trying?
I would use electrical contact spray, and let it dry...I always disconnect battery when swapping.

On weathered connections, I slap some di-electric grease on them before plugging back in.

Image

mhgreen
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Year and Model: 240 DL 1986
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Post by mhgreen »

I replaced ECU with a working used part. I can now plug IAC in and all is well. Cleaning the terminals was a good idea anyway on the connector, so I went ahead and did that. I just hope this ECU doesn't burn up somehow - - especially considering I am not sure what caused the failure on the last one that was in there.
“Some cannot loosen their own chains and can nonetheless redeem their friends.”

lummert
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Post by lummert »

Now that the problem is solved, take the cover off the bad ECU and look for something gone wrong.
1988 Volvo 760 Turbo Wagon

mhgreen
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Year and Model: 240 DL 1986
Location: Portland, OR

Post by mhgreen »

lummert wrote:Now that the problem is solved, take the cover off the bad ECU and look for something gone wrong.
I took it apart, but I am not even remotely sure of what to look for! There is a lot going on under there
“Some cannot loosen their own chains and can nonetheless redeem their friends.”

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93Regina
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Post by 93Regina »

mhgreen wrote:I am not even remotely sure of what to look for
Bad capacitors

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