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Where is the Upshift Delay Switch?

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I've been getting a code 26 on my 1995 E320. According to the manual, the uplift delay switch has a problem. In a previous posting, someone suggested testing the switch to see if it hold vacuum. Mine does not, so I'm assuming either the switch is faulty or the vacuum line to the switch has a leak. I was just under the car trying to locate the switch. I was able to trace the green vacuum line to the top of the transmission on the passenger side, but I could not find the end. Does anyone know where the switch is located and if I can reach it without having to drop the transmission? Any help would be appreciated. Bob

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Right here.

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Thanks, Robert. I'll go under the car again to see if I can locate it. Looks like it's located on the passenger side of the transmission. Sure hope I can figure out how to remove it since there's not a lot of room between the chassis and the transmission to see how things are assembled. Will let you know if I'm successful.

Bob

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I've never done it but, I remember reading about changing a B2 piston on a W124 with the transmission still in the car.

Seems to me that the writer put the car on jack stands then placed a jack under the transmission. After removing the rear mount, let the transmission down as far as it would safely go while prying the right rear with a 2X4.

He says this gave him enough room to do the job. By the way, B2 piston is on the same side you will be working on except it is closer to the rear.

Maybe some else out there has actually done this job and can shed some light on the proceedure.

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Re: Where is the Upshift Delay Switch?

Bob J;93465 wrote:
I've been getting a code 26 on my 1995 E320. According to the manual, the uplift delay switch has a problem. In a previous posting, someone suggested testing the switch to see if it hold vacuum. Mine does not, so I'm assuming either the switch is faulty or the vacuum line to the switch has a leak. I was just under the car trying to locate the switch. I was able to trace the green vacuum line to the top of the transmission on the passenger side, but I could not find the end. Does anyone know where the switch is located and if I can reach it without having to drop the transmission? Any help would be appreciated. Bob

I also have code 26 showing on my '94 E320. The code list I looked at said "upshift delay switchover valve, open or short". My understanding is that the "switchover" valve is located in the engine compartment, on the left (driver's) side of the firewall. There has been disagreement by local mechanics at re. "switchover" valve or actual "delay" valve (modulator?). After some back and forth I took the car to an independent Mercedes specialist in a near by town. They want to replace the infamous wiring harness before attempting to diagnose code 26. Their rationale is that they can't reliably diagnose problems with the original harness. Their position seems defensible as I can see several places with bare wire visible, especially at component connecters. Any feedback will be appreciated; be as technical as you want in any replies, I used to be an SCCA racer and have built both race and street engines - otherwise this is my first Mercedes.

Also my first post, I just joined a few weeks ago. I'm very impressed with the quality of information.

Tom

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Re: Where is the Upshift Delay Switch?

I don't own a gas car so I'm kind of guessing here. If the readout says "switchover" I would assume it is the one under the hood and not the shift point retard solonoid valve located on the transmission.

Testing of the switchover valve is not complicated. It has 2 wires for the coil and appears to accomodate 3 vacuum hoses. Pull the connector off the valve and measure contuity across the coil. If open, replace. Alternatively, use a pair of clip leads and ground one of the terminals while touching a lead from the other to the positive terminal of the battery. If there is no audible click, the solonoid is open and must be replaced.

Note the 3 hose barbs and 2 hoses on the valve. The one at the top should have a little rubber cap on it to block it off. If missing, place a piece of tape over it and test drive the car if it drives well, get a cap.

Last thing, or first, if that's where you want to start, is to check the vacuum switch with a Mighty Vac or similar tool. Don't forget to cap the top opening on the valve when performing the test.

Hopefully, someone with a similar W124 can comment on the accuracy of the 3 hose barbs on the valve.

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Re: Where is the Upshift Delay Switch?

Robert,
Thanks for the reply to "upsift delay switchover..."

Incidently, I graduated from Virginia Weslyan college in Virginia Beach... somewhere back in the early 70's; was also stationed at Fort Story, VA for a few months while in the Army. I bet Virginia Beach has changed from the way I remember it.

Tom

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Re: Where is the Upshift Delay Switch?

Hang on to your memories of Virginia Beach. It just ain't the same any more.

Also be advised that what happens in Virginia Beach stays in Virginia Beach.

Because of the traffic.

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