On Board Diagnostics

Electronic Throttle Module (ETM) Rebuild Service

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On-Board Diagnostic Codes

(For a full description click on Decoding OBD On-Board Diagnostics)

The Check Engine light, or Malfunction Indicator Lamp" (MIL as it is called today) tells the operator that something within the vehicle is not operating as is should. It may come on and go off, stay on or flash. But it says that something is not working right. It might be as simple as a loose gas cap which is part of the emission system or a more serious problem. Imagine heartburn for that highly spicy dinner or a gall bladder attack, same symptoms, different severity.

Someplace in the vehicle, probably in the front console or under the steering column, is a connector about 2" long by 1/2" wide that connects to the various computers. The mechanic or technician will plug in a code reader and tretrieve any saved OBD codes. The numbers displayed will give an indication of the problem. These are not exact but give strong clues as to where to look for the problem. In Volvos, if a trouble code is detected it is recorded as "PENDING". If on the next driving cycle (turning off the engine and restarting, think getting gas or a Whopper) the same code is detected, it is recorded and saved. If no code is recorded on the next driving cycle the "PENDING" code is erased.

There are two types of codes, the generic (SAE/ISO) which are the same for all vehicles and mostly relate to emission problems such as a misfiring cylinder. Enhanced codes (Volvo DII) are added by the manufacturer to be specific for the vehicle (Think Champagne cooler in a Bentley saying it is too warm). So there are many codes that might relate to an Electronic Throttle Module. The codes most specific to the ETM are shown below:

(You can generally Google, Volvo + the diagnostic code and find a discussion of the code).

Diagnostic code P-0106, special conditions

P-0106 code must be solved prior to condemning an ETM. Using a generic scan tool on your car could be misleading in a lot of cases. For example; if your car is not equipped with a Manifold Absolute Pressure (MAP) sensor and your scan tool is “saying” that it is, most likely it is a Mass Air Flow (MAF) sensor that is generating this code. MAF failure will cause the symptoms you are experiencing.

The following steps should be taken;

Have a local Volvo dealer or specialist pull out the codes from the ECM using a VIDA tool or equivalent.
Repair or replace necessary components.
If problem with surging still persist and no codes are stored it could be an internal problem within the ETM. It is not unheard of to have defective new ETM units right from the factory or once that have failed soon thereafter.

Also, if the eighth letter in your VIN number is D, N or R then the Volvo catalog lists a MAP sensor. It is located on top of the gas tank. This sensor monitors the pressure in tank and has nothing to do with the symptoms you have described or the “real” MAP sensor. For whatever reason catalog people decide it to name it MAP as well.

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On-Board Diagnostic Codes

ISO/SAE Generic codes	Volvo VII (DTC)	Diagnostic trouble code designation	Fault type	These are abbreviated descriptions of the fault. (The comments in italics are my thoughts on the matter.)

P0220	ECM-9150	Throttle unit, internal fault	Faulty signal	Fault with potentiometer number 1. The most common fault of this type is that a difference of more than 5% is detected between potentiometer 1 & 2 for 0.2 seconds or longer. (I bet this is one of the parameters they loosened in the software recall.)
P0221	ECM-914F	Throttle unit, internal fault	Faulty signal	This DTC was only used in 1999 Model year 5&6-cylinder turbo and 6-cylinder non turbo vehicles, and is triggered if the ETM detects tht the signals from throttle position sensors 1&2 differ by more than 5% while driving.Downloading the latest ETS software will remove this DTC as the monitoiring of the potentiometers is changed.
P0225	ECM-9150	Throttle unit, internal fault	Faulty signal	Fault with potentiometer number 2. The most common fault of this type is that a difference of more than 5% is detected between potentiometer 1 & 2 for 0.2 seconds or longer. (I bet this is one of the parameters they loosened in the software recall.)
P1600	ECM-9190	Throttle unit, internal fault	Faulty signal	The fault indicates an under of over-current in the drive circuit fo the throttle motor.--- or that the throttle blade does not move despite a large current applied to the motor. (It's stuck, sounds uncommon.)
P1601	ECM-91F0	Throttle unit, internal fault	Faulty signal	This fault is detected if the current applied to the throttle motor does not correspond to the measured current consumed by the motor. (Check for low battery voltage)
P1602	ECM-91B7	Throttle unit, internal fault	Faulty signal	This fault code indicates that the throttle blade was not in the expected position when the ETM was powered up. Check that no foreign objects are blocking the throttle. (This is a case where cleaning might make a diference.)
P1603	ECM-91A7	Throttle unit, internal fault	Faulty signal	This fault is detected by the ETM and uses the power consumption of the throttle motor, to determine possible high friction in the throttle.
P1604	ECM-910E	Throttle unit, internal fault	Faulty signal, Intermittent fault	The ETM has detected a problem with either its memory or central processor, and has requested that the ECM post this fault.
P1604	ECM-910E	Throttle unit, internal fault	Faulty signal, Permanent fault	This is most often set as a secondary fault when a CAN *(computer network) glitch occurs for more the 0.5 seconds, as the ECM may change its requested angle, but the actual angle reported from the ETM does not change do to the loss of CAN signal.
P1608	ECM-903F	Throttle unit, internal fault	Signal too low or signal missing	The actual throttle angle reported by the ETM to the ECM do not agree by more than a predetermined limit.
P1609	ECM-903F	Throttle unit, internal fault	Signal too low or signal missing	The actual throttle angle reported by the ETM to the ECM do not agree by more than a predetermined limit.
P1610	ECM-903F	Throttle unit, internal fault	Signal too high	The actual throttle angle reported by the ETM to the ECM do not agree by more than a predetermined limit .
P1611	ECM-902A	Throttle unit communication	Signal too high or signal missing	This monitor will trigger a fault if the information sent from the ETM to the ECM over the CAN (communications bus) is missing for more than 0.5 seconds. (Potentiometer wear could cause this missing signal.)
P1612	ECM-902A	Throttle unit communication	Signal too low	This monitor will trigger a fault if the information sent from the ETM to the ECM over the CAN (communications bus) is missing for more than 0.5 seconds. (Potentiometer wear could cause this missing signal.)
P1613	ECM-902A	Throttle unit communication	Signal too high or signal missing	This monitor will trigger a fault if the information sent from the ETM to the ECM over the CAN (communications bus) is missing for more than 0.5 seconds. (Potentiometer wear could cause this missing signal.)