Hello all,

Recent purchase 1996 Volvo 850 base model (115k miles) that went into "limp home mode" last night with flashing shift arrow indicator and check engine light. Tried shut down and restart when I got it home with no change. This morning the shift arrow cleared itself but the check engine light was still on. Autozone read "P0743 Gear 4 Ratio Incorrect" and cleared the check engine light for me. Car now drives perfect again with all shifts working great.

I have researched multiple posts and I suspect a bad PNP switch but I'm also wondering if I have a bad ABS control module? Previous owner records show he had similar problems several times during the last year with code "324" for incorrect gear ratio for S1 and S2 solenoids AND multiple codes for a bad ABS control module. Does not look like he replaced the ABS module but just had the codes cleared when this happened.

So is my problem most likely the ABS module or the PNP switch?

ABS module thoughts:
I'm thinking a bad ABS module might cause the "incorrect ratio" codes? From what I've read the ABS module looks at engine vs wheel rotation speed in the various gear ratios so a failing module might generate this code?

PNP switch thoughts:
I suspect the flashing shift arrow indicator cleared due to my running the shift lever through all gears (I think I read that this cleans the contacts for the PNP switch?)

Thanks for any info!
Paul Klusman
1996 Volvo 850 Base Model

 

The ABS module should not turn on Incorrect Gear Ratio code.

I would first check the tranny fluid level. A low fluid level, as little as a half quart, sometimes triggers the code. If topping up does no good, then you may want to replace the PNP.

I would consider this guy for the ABS module repair & upgrade but there are other vendors available: http://home.earthlink.net/~vicrocha/

Wait for others’ inspirations as well.


JPN

 

Thanks for the info, JPN! ABS module repair and upgrade looks like a good option.

Paul

 

Also if you are handy check out this post. I have done about 10 of them myself with no problems.

https://volvoforums.com/m_58856/tm.htm

 

Excellent! I'll probably give this a try. Thanks!

Paul

 

Best of luck, and try not to touch the soldering points as some of the SMD (Surface Mount Device; transistors, resistors, capacitors, diodes, IC, LSI, etc...) may get damaged by static discharge from your finger[:@].

For 1995 or older ABS, I did a bit of research in the past and onetechnician in Japan said that the ABS-related troubles on these cars are usually not the module but the brake switch and something else. I will see if I can find the info somewhere this weekend.


JPN

 

Been driving fine for three days, now. Apparently an intermittant problem but I'm sure it will happen again. I run the shift selector through all positions every time I drive. Hopefully this helps.

Thanks for all the advice, guys!

Paul

 

No prob, Paul. Please give us updates or fire away with questions anytime you need to.


JPN