I am trying to troubleshoot what I think is an electrical/computer issue that is related to an overvoltage situation resulting from a bad voltage regulator.

The Backstory:
The wife was driving the car one morning when she received awarning message on the dash reading something along the lines of “overvoltage,pull car over safely”. She was almost home so she continued to drive the car for a couple miles or so. She broke down about a block from the house. We towed the car home that afternoon, determined that a bad voltage regulator was the culprit, and replaced the part.

After charging the battery overnight, the car started right up and the overvoltage display on the dash disappeared, but the car was idling erratically and in “limp mode”. Wont rev over ~2,500 RMP. So we reset the computer and cleaned the throttle body for good measure. The idle seems to be smoother but the car is still in limp mode.

Current Situation:
The code scanner is pulling; P2177, P0507, P0037

And I am suspicious that the DDM, PDM, and REM modules are coming up as “checking” when I run the DTC module scan on the dash. All other moduleare coming up as “set”.

I have a new O2 sensor in the mail to clear the P0507 code, but I don’t think that’s going to solve my limp mode issue as that code was an existing problem prior to this event.

I have limited experience with these cars and electrical/computer issues in general. My fear is that the overvoltage situation may have caused electrical problems that are responsible for the current limp mode status.

Any help or insight is greatly appreciated.

 

Turbo or non-turbo?

 

non-turbo

 

I would check for vacuum leaks. Specifically the hose from the intake to the MAP sensor above the radiator.

 

checked for air leaks around the map sensor. appears to be no leaks.

checked the manifold air pressure read out and im getting:
64 kpa @ idle
27 kpa @ 2500 rpm

also changed out the O2 sensor which cleared the P0037 code, but did not resolve any of the current symptoms

 

How did you clean the throttle?

 

throttle body cleaner, a tooth brush, and a rag.


It had no effect on the codes, they were the same before and after the cleaning.

 

Did you spray it into the throttle directly? Might have a bad throttle.

 

the symptoms were the same prior to and after cleaning the throttle body.


is there a procedure to test the throttle?

 

I'd be curious if there are any other codes stored that a generic scanner can't read.

P2177 doesn't show as a code to correlate to a Volvo specific code for the non-turbo engine.

P0507 corresponds to ECM-620A which has no fault tracing. Possible sources are air leakage, blocked or sticking throttle, blocked PCV system or clogged oil pan (likely the passage from the PCV).

 

yea, I'm on Kauai, there are only one or two guys on the island that work on Volvos $$$$$$$


I'll keep looking for vacuum leaks and check the PVC valve.


Thanks for your help.

 

I know you said you replaced the Voltage Regulator but are you sure something else isn't wrong with the Alternator?