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1998 S70 PnP switch 9466012, bad aftermarket new part Topic is solved

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ferocity02
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1998 S70 PnP switch 9466012, bad aftermarket new part

Post by ferocity02 » Tue Jan 30, 2018 10:57 am

I have a 1998 Volvo S70 GLT that I've been having an ongoing issue with. Every now and then, the transmission will throw an error for low signal from the transmission range switch, code AT-124. This is accompanied by a check engine light and the transmission getting stuck in 3rd gear. This seems to happen most often when parked. It rarely happens when driving.

First, I took apart the factory switch, cleaned the contacts and filed them back to shape. This did not make much difference.

Then I replaced the switch entirely with a new non-OEM part. This sort of worked. The issue became less common after this, but not totally gone.

About a year goes by without any trouble and it just started acting up again, and it's doing it quite often, every other day roughly. This suck because I have to smog soon and I can't pass with a check engine light.

Anyone have any suggestions?

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wizechatmgr
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Re: Ongoing issue with Transmission Range Switch

Post by wizechatmgr » Tue Jan 30, 2018 11:25 am

I'd test both old and "newer" switch to see if either is good with a multi-meter. The problem with intermittent issues is they're damn hard to nail down during testing.
Wisdom requires knowledge as a prerequisite, but knowledge can be developed due to a lack of wisdom.
In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD - ~190k miles

ferocity02
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Re: Ongoing issue with Transmission Range Switch

Post by ferocity02 » Tue Jan 30, 2018 12:34 pm

Like you said, because the issue it intermittent, I can test all day and never have see an issue. I did test both at one point and they were fine.

Some searching suggested that it may actually be an issue with the S/E/W drive mode swtich. If the TCM loses signal from it for 25 sec it will throw the same code. So I'm going to see about cleaning this switch tonight.

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wizechatmgr
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Re: Ongoing issue with Transmission Range Switch

Post by wizechatmgr » Tue Jan 30, 2018 1:37 pm

Couldn't hurt :)
Wisdom requires knowledge as a prerequisite, but knowledge can be developed due to a lack of wisdom.
In order to learn how to fix something, you must first learn how to break it.
1999 V70 XC AWD - ~190k miles

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FLXC90
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Re: Ongoing issue with Transmission Range Switch

Post by FLXC90 » Wed Jan 31, 2018 6:44 am

Makes sense, mode switch is in a likely position for contamination by spills. If it goes into W mode, there's your third gear start :roll:
Current Volvos:
1998 V70 T5, 112k sat 5 years, still in mechanical coma (finally at the top of the pile )
2004 XC90 T6 AWD: 186k, 60 on transaxle ( traded in )
1998 POS70 N/A: DD/training aid, 236k but really about 240k, I think...ABS module( passed on to son who sold it)

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RickHaleParker
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Re: Ongoing issue with Transmission Range Switch

Post by RickHaleParker » Wed Jan 31, 2018 4:18 pm

I think you got an intermittent short that puts the transmission in Winter mode.

43: AT-124 Mode selector switch

DTC information


A4300770 Condition
The driving mode selector allows the driver to select from three modes: Winter (W), Economy (E) and Sport (S). The mode selector has two signal cables, MS1 and MS2, and a ground lead. Driving mode is selected by connecting one or the other, or both signal cables to ground (the signal goes low). Note that MS1 and MS2 signal cables are grounded simultaneously only when the W button is depressed.
B=battery voltage
G=ground (Ulow)

Diagnostic trouble code (DTC) AT-124 is posted if the transmission control module (TCM) registers that the signal is low (low voltage) in both signal cables simultaneously for at least 25 seconds.
Caution! This diagnostic trouble code (DTC) can be posted if the W button is depressed for more than 25 seconds
^^^^ a short could do this ^^^^^^

Substitute value
The transmission will only operate in driving mode Economy (E).

Possible source
  • Short-circuit to ground in signal cables
    Defective mode selector.
    The W button has been depressed for more than 25 seconds.
Fault symptoms
The transmission operates in driving mode E.
--------
Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
Platform P2 2004 S60R, B2524T4, AW50/51 AWD, B8444S TF80 AWD, Bosch Motronic 7.0, BorgWarner K24 turbocharger. V8 conversion in progress.

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BEJinFbk
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Re: Ongoing issue with Transmission Range Switch

Post by BEJinFbk » Wed Jan 31, 2018 7:19 pm

FLXC90 wrote:
Wed Jan 31, 2018 6:44 am
Makes sense, mode switch is in a likely position for contamination by spills. If it goes into W mode, there's your third gear start :roll:
For this very reason, my console is virtually always
protected with a small, charcoal colored dish towel...

It may not show off the pretty fake wood trim,
but if my coffee sloshes, I'm good! :mrgreen:
'98 V70 R - Well Equipped for Life Up North... ;)

ferocity02
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Re: Ongoing issue with Transmission Range Switch

Post by ferocity02 » Sun Feb 11, 2018 7:56 pm

Ok guys... I tried holding the "W" button down for 25 seconds and it did not error out the transmission. Not sure what to make of that... I went ahead and replaced this switch anyways and I got the AT-124 error again a couple days later. The original was clean inside.

The last time I saw the moment the transmission errored was as I was putting it into park. So today I messed with the alignment of the PNP switch. With the switch rotated all the way to one side, I recreated the AT-124 error where putting it into will park with throw the code, several times. So I rotated it all the way to the other side and no error. Reverse lights still work. It's not aligned perfectly but I'm going to give it a shot. So far so good.

ferocity02
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ferocity02

Re: Ongoing issue with Transmission Range Switch

Post by ferocity02 » Mon Feb 12, 2018 1:20 pm

The AT-124 code came back...

Things I've tried so far:
-Cleaned PNP switch
-Replaced PNP switch
-Adjusted PNP switch
-Replaced S/E/W mode switch
-Checking wiring and connections at these switches

The fault is intermittent so it's a real pain to diagnose.

Any more ideas? Need to smog soon but can't with the Check Engine light. When I smogged 2 years ago the transmission faulted DURING the smog test. Of course the transmission waits until smog time again to start acting up.

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RickHaleParker
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Re: Ongoing issue with Transmission Range Switch

Post by RickHaleParker » Mon Feb 12, 2018 1:35 pm

Probe for shorts in the cable to the mode selector.
--------
Platform: P80 1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
Platform: X40 (Nedcar) 2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
Platform P2 2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
Platform P2 2004 S60R, B2524T4, AW50/51 AWD, B8444S TF80 AWD, Bosch Motronic 7.0, BorgWarner K24 turbocharger. V8 conversion in progress.

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