94' Vacuum Modulator

[sierra1boy]

Hi Guys,

So I'm chasing down a CEL 71 on my 94 and am thinking of replacing my vacuum modulator since it does look old. The question I have is with the part number. Throughout the other threads I have always seen this part number for it: 25870-66011. However, I looked at mine and its has a different part number on it 25870-16240. Does anyone know if that is the original number for a 94'? I want to rule out that some prior owner just replaced it with the wrong part. thank you

 

[voodu3]

It looks like 25870-66011 is the new part number.

 

[Fj80oregon]

660

Hi Guys,

So I'm chasing down a CEL 71 on my 94 and am thinking of replacing my vacuum modulator since it does look old. The question I have is with the part number. Throughout the other threads I have always seen this part number for it: 25870-66011. However, I looked at mine and its has a different part number on it 25870-16240. Does anyone know if that is the original number for a 94'? I want to rule out that some prior owner just replaced it with the wrong part. thank you

View attachment 3720126

why not test the modulator per the FSM and clean it out. It’s a super simple diaphragm design.
66011 is the correct number.

 

[BTLSHP]

FWIW, our '94 has had CEL 71 problems several times over 235k miles. When I went after it this summer I looked at the records, the vacuum modulator has never been the issue. Usually the invoice says something about cleaning the pintle in the EGR valve. This summer I found the tube molded into the upper intake manifold to be mostly clogged with carbon deposits as well as a sticking pintle.

The vacuum modulator is easily tested and pretty fool proof to begin with. I think the felt can get dirty, but ours was clean at 30 years old.