Can't get TPS voltage above .15 volts - part 2

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90topdown said:

With selector set on 200 ohm

Resistance between TPS black wire and disconnected neg batt cable- .4 ohm

Resistance between EGR black wire and disconnected neg batt cable- -1- (meter never moved)

Resistance between MAP black wire and disconnected neg batt cable- -1- (meter never moved)

Looks like the problem is in the injector harness somewhere.

Next step is pull the injector harness and unwrap it and see where the problem is??

Click to expand...

2003 PCED OBD SECTION 2: Diagnostic Methods
Procedure revision date: 12/19/2002

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Basic Circuit Checks
Description
Basic circuit checks help to minimize pinpoint test steps by providing a procedure to diagnose harness faults associated with the Electronic Engine Control (EC) System. The following techniques provide helpful reminders for diagnosing open circuits (continuity), shorts to ground and shorts to power.

NOTE:

The suspect circuit must be isolated before testing.
When disconnecting any harness connector, always inspect for damaged or pushed out pins, corrosion and loose wires. Repair as necessary.
The digital multimeter must be set to the correct scale.
The techniques do not apply in all situations, therefore, it is necessary to follow each pinpoint test step accurately and completely.
General resistance and voltage values are specified below. Always use the pinpoint test values if they differ.
Always turn the key to the OFF position unless directed otherwise by the pinpoint test.
Each of the following procedures will require the powertrain control module (PCM) and component to be disconnected to isolate the harness.

Open Circuit (Continuity)
Disconnect PCM. Measure the harness resistance between the suspect circuit at the harness connector and the appropriate PCM harness connector pin or PCM breakout box (if available). The resistance must be less than 5.0 ohms.

Shorts to Ground
Measure the harness resistance between the suspect circuit at the harness connector and a reliable ground (B-, chassis gnd or PWR GND at the PCM breakout box, if available). The resistance must be greater than 10,000 ohms.

Shorts to Power
Key ON to power up circuit. Measure voltage between the suspect circuit at the harness connector and a reliable ground. The voltage must be less than 1.0 volt.




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any update?

just checking to see if you found it yet,,,im no pro here but if the injector harness is unplugged,and he did a continuity check on say pin47 of tps to pin in the plug only 47 should read and all other pins no,and if it did the shorts in harness,,,ang than check the rest one by one,,,or is that not proper?

its been quiet?

hey how are things going now,,any luck

tps

looking for an update ,,,Did you find your problem yet? was reading today and came across this.............EFI SYSTEM TIPS
Always remember to disconnect the battery before doing any wiring on your vehicle!
ELECTRICAL GROUNDS
The single leading cause of most electrical problems is poor grounds.
Ideally, the ground for the fuel injection system should connect directly to the battery at the negative post. Using the steel chassis or engine block as a
ground can create excessive resistance causing the Powertrain Control Module (PCM) to function improperly.
An example of how a high ground or connection resistance can have very serious effects is as follows. This particular case applies to a 2005 Mustang GT,
but can easily be extended to any electronically controlled Ford vehicle: consider the case where a PCM is reading a MAF sensor signal of 4.1 V (due to a
high ground or connection resistance) when it should really be reading 4.3 V. This equates to a difference in measured air mass of 13%. That is, the MAF
will be telling the PCM that there is 13% less air entering the engine than there really is. Let’s say this happens at WOT, where air/fuel ratio is critical not
only to performance, but also to engine durability. The result is that the actual air/fuel ratio can go from a safe 12.5:1 to a potentially damaging 14.1:1, just
from a 0.2 V change in the MAF return signal!
All PCM sensors, not just the MAF, are affected in a similar fashion, so it is absolutely critical that all electrical connections are solid and that the grounds are
reliable. The potential penalty for a bad ground can range from strange drivability issues that are difficult to diagnose all the way to a damaged engine, as in
the above example.
All resistance tests should be done with the ignition key in the off position. Having voltage going through the system can return a false reading of excessive
resistance. Additionally, it is possible to have a ground that tests OK when the engine is cold, but not when the engine is hot. Heat increases resistance, so
these tests should be performed on a warm engine when possible.
To test for an adequate ground circuit in the EFI system for a 1986 to 1993 5.0L Mustang, use a Volt/Ohm meter to check the resistance of the
following circuits:
• To verify a proper ground to the PCM, check the resistance from pin 40 and pin 60 DIRECTLY to the negative side of the battery. Resistance should be
no greater than 0.2 ohms.
• To verify a proper ground to the main PCM harness, check the resistance from the MAF sensor at pin ‘B’ DIRECTLY to the negative side of the battery.
Resistance should be no greater than 0.2 ohms.
• To verify a proper ground to the engine harness, check the resistance from the black wire at the Throttle Position Sensor (TPS) DIRECTLY to the
negative side of the battery. Resistance should be no greater than 0.3 ohms.
Note that while 0.2 ohms or less is desirable, a resistance as high as 0.5 ohms is considered acceptable. Greater than 0.5 ohms is excessive and could
result in drivability concerns.
A weak ground connection can also cause the PCM’s internal reference voltage regulator to function incorrectly. This can be checked at the Throttle Position
Sensor (TPS) by checking voltage between the black ground wire and the orange reference voltage wire. With the key on, this voltage signal should be
somewhere between 4.7 V and 5.3 V.
general tips
• Whenever possible, the PCM should be mounted inside the vehicle to protect it from water damage. The PCM should also be mounted with the electrical
connectors at the bottom to avoid trapping water. Some PCM’s on newer model cars are mounted under the hood, but they are sealed against moisture
and designed to operate in such an environment. When in doubt, mount the PCM inside the vehicle.
EFI SYSTEM TIPS
Always remember to always disconnect the battery before doing any wiring on your vehicle!
ELECTRICAL GROUNDS
The single leading cause of most electrical problems is poor grounds.
Ideally, the ground for the fuel injection system should
connect directly to the battery at the negative post. Using
the steel chassis or engine block as a ground can create
excessive resistance causing the Powertrain Control
Module (PCM) to function improperly.
An example of how a high ground or connection resistance can have very serious effects is as This particular case applies to a 2005 Mustang GT, but can easily be extended to any electronically
controlled Ford vehicle: Consider the case where a PCM is reading a MAF sensor signal of 4.1 a high ground or connection resistance) when it should really be reading 4.3 V. This equates difference in measured air mass of 13%. i.e.: The MAF will be telling the PCM that there is 13% entering the engine than there really is. Lets say this happens at WOT, where air/fuel ratio is only to performance, but also to engine durability. The result is that the actual air/fuel ratio can safe 12.5:1 to a potentially damaging 14.1:1, just from a 0.2 V change in the MAF return signal!
All PCM sensors, not just the MAF, are affected in a similar fashion, so it is absolutely critical electrical connections are solid and that the grounds are reliable. The potential penalty for a bad can range from strange drivability issues that are difficult to diagnose all the way to a damaged in the above example.
All resistance tests should be done with the ignition key in the off position. Having voltage going the system can return a false reading of excessive resistance. Additionally, it is possible to have ground that tests OK when the engine is cold, but not when the engine is hot. Heat increases so these tests should be performed on a warm engine when possible.
To test for an adequate ground circuit in the EFI system for a 1986 to 1993 5.0L Mustang, use Ohm meter to check the resistance of the following circuits:
• To verify a proper ground to the PCM, check the resistance from pin 40 and pin 60 to the negative side of the battery. Resistance should be no greater than 0.2 ohms.
• To verify a proper ground to the main PCM harness, check the resistance from the sensor at pin ‘B’ DIRECTLY to the negative side of the battery. Resistance should be than 0.2 ohms.
* Not legal for sale or use on pollution-controlled motor vehicles. **Direct replacement part.
See pages 3-9 for important safety, emissions and warranty information.
EFI TECH