No-start on 1995. The error codes displayed C72 H53 H72

[starbuck]

Jumped pins 4 & 12 on the pseudo-OBD port and pulled the following codes.

Module 1
c72
h53
h72

module 4
---
module 9
---

A
ERR

I'm pretty sure the H72 code is there because of the non-factory radio
The C72 ?)
the H53---Isn't that VATS related?

 

[John Robinson]

Jumped pins 4 & 12 on the pseudo-OBD port and pulled the following codes.

Module 1
c72 C Indicates current reading

h53
h72 H indicates stored history

I will be sending more information in a few min.

module 4
---
module 9
---

A
ERR

I'm pretty sure the H72 code is there because of the non-factory radio
The C72 ?)
the H53---Isn't that VATS related?

The mataerial I will be sending is from my 93 FSM but I believe it is pertinent toyour 95 as well. My FSM says the code information I have is for cars up through 95 o

 

[John Robinson]

Note the items I have highlighted. As I previously said do not let the codes fool you into believing a particular part is to fault. Note how the TPS(Throttle Position Sensor) Can effect the Gear selector switch circuit.

Hope this sheds some light on thetps for you

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​

ThrottlePosition Sensor (TPS)
Copied from 1993 Service Manual​

The Throttle Position sensor (TPS)is a potentiometer connected to the throttle shaft on the throttle body. It isa potentiometer with one end connected to 5 volts
from the ECM and the other to ECM ground. A third wire is connected to the ECMto measure the voltage from the TP sensor. As the throttle valve angle ischanged (accelerator pedal moved), the voltage output of the TP sensor alsochanges. At a closed throttle position, the voltage output of the TP sensor islow (approximately .5 volt). As the throttle valve opens, the output voltageshould be approximately 5 volts.

By monitoring the output voltage from the TP sensor, the ECM can determine fueldelivery based on throttle valve angle (driver demand). A broken or loose TPsensor can cause intermittent burst of fuel from the injectors and cause anunstable idle, because the ECM detects the throttle is moving.

If the TP sensor circuit is open, the ECM will set a DTC 22. If the TP sensorcircuit is shorted a DTC 21 will be set. A problem in any of the TP sensorcircuits will set either a DTC 21 or 22. Once a DTC is set, the ECM will use adefault value for TP sensor, and some vehicle performance will return.

A personal note, when my TPS failed it DID NOT set a code other than totell me the ECM was bad.

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​

 

[starbuck]

Keep getting "err" on module 9.1 readout

 

[Hib Halverson]

For MY95 Module 1 C72 is LCD dimming circuit open or shorted. If you have an aftermarket receiver installed and did not make the proper wiring harness modification, that code will set all the time

H53 is a history code for a PASS-key fault
H72 is a history code for the LCD dimming circuit which I'd expect to find if you have an aftermarket receiver installed w/o the proper harness mod.

Err on module 9 means the CCM cannot communicate with the EBTCM.