Hey guys, i recently ran into two codes one was the p0600 and the other one i forget but it was something to do with the IAC. Im going to replace the IAC tomorrow but am stumped on what the p0600 code could be. Everything is fine with my truck besides a high idle which i assume will be fixed with the IAC. Also this p0600 code popped up a week after the IAC code. Hope someone knows! Thanks!

 

I never experienced a P0600. This is one result from one look-up site.

P0600 OBD-II: Serial Communication LinkOBD-II Code P0600 is defined as a PCM Serial Communication Link Malfunction

The PCM or Power Train Control Module performs many vital functions in a modern vehicle, such as management of the Fuel System, Ignition System, Transmission, Anti-Lock Brake and Traction Control systems. The Serial Communication Link enables the control modules to 'talk ' to each other.

When the code P0600 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM has lost communication with 1 or more other control modules.

Driving with this trouble code is not recommended
A vehicle with this code should be taken in to a repair shop for diagnosis.

P0600 Symptoms

• Check Engine Light will illuminate
• ABS/Traction Control Light may illuminate
• Transmission Light May Illuminate
• Vehicle may not perform and/or shift properly
• Decrease in fuel economy
• In some cases, there may be performance problems, such as dying when coming to a stop and/or misfire-like symptoms
• In unusual cases, there are no adverse conditions noticed by the driver

Common Problems That Trigger the P0600 Code

• Defective PCM (Power Train Control Module )
• Defective PCM data bus wiring/connections
• Defective PCM data bus ground circuit(s)
• Defective PCM or other control module controlled output devices
• Defective CAN bus communication

Common Misdiagnoses

• Ignition problems whose root cause is a defective PCM
• Fuel Injection problems whose root cause is a defective PCM

P0600 Diagnostic Theory for Shops and Technicians

The PCM shares data input with several different systems and if the communication link between them fails, then 1 or more systems will shut down. The cause of the P0600 code may be a defective data bus, a defective data bus connection, or a defective control module. If you have to replace a module, make sure that you inspect all of the module's output devices and wiring for shorted circuits or else the new module will fail in short order. When diagnosing a P0600 code, it is important to record any other codes and the P0600 freeze frame data. Then one should duplicate the code setting conditions with a test drive. Pay close attention to the engine load, throttle position, RPM, and road speed because a P0600 can be difficult to detect.

 

Welcome to the forum

Should always post the year of the Ranger with questions, also engine model as well

P0600 Serial Communication Link Malfunction

ignore it, most likely came from your OBD2 reader

There are several IAC Valve codes
P0505 Idle Control System Malfunction
P0506 Idle Control System RPM Lower Than Expected
P0507 Idle Control System RPM Higher Than Expected

There are MORE

Codes mentioning a sensor or control(IAC is a control) rarely mean the sensor or control is bad, these are diagnostic codes, so help the human brain to diagnose a problem


Always look up any OBD code on a full list, like this one: https://www.therangerstation.com/tec...II_codes.shtml

Its a Ford list
That way you can see the codes the Computer DID NOT USE, which are as important as the code it did use, diagnostics is about information

If you have a high idle then P0507 could be expected, but not an IAC Valve issue, could be a vacuum leak which is alot more common than IAC Valve failure

 

Thank you! My bad my ranger is the 2.5l with the 5spd.
I just took a look at the IAC code that came up and it is p1506.

And I'm confused about the p0600, did the obd just make a mistake? I should just ignore?

 

Yes, assuming 1998-2001 Ranger(years that had 2.5l) the only serial communications is between Computer and OBD reader when its connected
ABS module may have a serial connection, and maybe SRS(seatbelt/airbag) system, lack of "communication" with these would, of course, cause no running issues

If it comes back remove the large 104 wire connector from computer in engine bay firewall, have a look for corrosion inside, then plug it back in, the unplugging and plugging in cleans the pins and slots in case there was some connection issue
Pins 15 and 16 are the serial BUS wires


P1504 Idle Air Control Circuit
P1505 Idle Air Control System At Adaptive Clip

P1506 Idle Air Control Overspeed Error

P1507 Idle Air Control Underspeed Error
P1508 Idle Air Control Circuit Open
P1509 Idle Air Control Circuit Shorted
P1510 Idle Signal Circuit

Computer did NOT use a "circuit" code, so most likely the IAC valve wiring and internal "circuit" are OK
After engine is warmed up and idling high
Unplug the 2 wire connector on IAC Valve
With no power IAC Valve will close and RPMs should drop, engine may even stall IF(big if) IAC valve was the reason idle was high

If RPMs remain high then IAC valve was not the reason, well 95% not the reason, lol, so most likely there is a vacuum leak causing the high idle

It is possible the valve inside is stuck open, so can't close
Pull off the IAC Valve and turn key on, engine off
Look at the valve inside, unplug and plug in the 2 wire connector, the valve should move back and forth, with and without power, it only moves 3/8" but can be seen moving
There will be a new code set from unplugging IAC Valve, a "circuit" code

If valve is not moving then replace IAC Valve
You can clean these, to get the valve unstuck, and moving again
Google: IAC Valve cleaning