How or where to read codes for a 1994 80 Series?? (1 Viewer)

Joined
Mar 31, 2010
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NW Arkansas
My neighbor's CEL came on in his 1994 80 series. :doh: He took it to Autozone and they said their machine couldn't read it. Anyone know what he should do?
 
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Columbia, MO
Last edited:
Joined
Feb 12, 2011
Messages
94
Location
Columbus, OH
Being an OBD1 truck, you can use the "paperclip method" to pull the codes.

1. Acquire paperclip
2. Open the hood, locate diagnostic plug on the passenger side firewall near the top. It's black and probably 1.5"x3".
3. Open cap to diagnostic plug, on the inside is a schematic of all the pin positions.
4. Remove the little metal jumper in the bottom right of the plug.
5. Get your paperclip, and jump terminals E1 and TE1.
6. Turn key to "ON" but don't start. CEL will blink. Codes are 2 digit, and there's a longer pause in between codes if there's more than one. They repeat indefinitely as long as you leave the ignition on.

Codes List:
OBD1 Codes
1Normal Condition.
2Air Flow Meter signal.
3Ignition signal.
4Engine Coolant Temperature Sensor signal.
5Oxygen Sensor.
6RPM signal (Crank Angle Pulse).
7Throttle Position Sensor signal.
8Intake Air Temperature Sensor signal.
9Vehicle Speed Sensor signal.
10Starter signal.
11Switch signal.
11ECU/ECM.
12Knock Control Sensor signal.
12RPM signal.
13Knock Control CPU (ECM).
13RPM signal.
14Turbocharger Pressure.
14Ignition signal.
21Oxygen Sensor.
22Engine Coolant Temperature Sensor signal.
23Intake Air Temperature Sensor signal.
24Intake Air Temperature Sensor signal.
25Air-Fuel Ratio Lean.
26Air-Fuel Ratio Rich.
27Sub Oxygen Sensor signal.
28No. 2 Oxygen Sensor signal.
31Air Flow Meter signal (Vacuum Sensor signal).
32Air Flow Meter signal.
34Turbocharger Pressure signal.
35Turbocharger Pressure Sensor signal.
35HAC Sensor signal.
41Throttle Position Sensor signal.
42Vehicle Speed Sensor signal.
43Starter signal.
51Switch signal.
52Knock Sensor signal.
53Knock Sensor signal.
54Inter-cooler ECM signal.
71EGR System.
72Fuel Cut Solenoid signal.
78Fuel Pump Control signal.
81TCM Communication.
83TCM Communication.
84TCM Communication.
85TCM Communication.
 
Joined
Feb 22, 2007
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176
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colorado front range north Lat: 40:23:57N (40.399
Mannnnnn- what the! I am getting code 25 and code 26 at same time. I did find a small hose under manifold disconnected and a big crack in the crank case manifold hose that connects to injection area to re-burn. My rig failed emissions this morning. Way high CO. Truck has O2 sensors that are couple years old. It's a 1994 80 with 235,k
 
Joined
Jul 26, 2016
Messages
214
Location
Portland OR
You can check your o2 sensors at the same terminal you used to check the codes.
Put a volt meter on DC volts and check the voltages at OX1 (first o2 sensor) and TE1 (ground)
You will be looking for a rapid sweep back and forth from .1v to.9v.
If you are running rich it will be running closer to .9v most of the time.
Running lean will run closer to .1v.

Your rear o2 sensor OX2 should not sweep that much since it is behind the cat. converter and should be closer to .1volts unless you are under load for a while. It should be more of a gentle sweep.

Hope this makes sense, good luck
 
Joined
Apr 14, 2016
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Oregon
You can check your o2 sensors at the same terminal you used to check the codes.
Put a volt meter on DC volts and check the voltages at OX1 (first o2 sensor) and TE1 (ground)

...

Your rear o2 sensor OX2 should not sweep that much since it is behind the cat. converter

I just wanted to note that on the 93/94 OBD-1 cruisers, the O2 sensors are parallel, rather than one before and one after the cat.

I just tried this on my '94 and it worked (sweeping voltage), but it seemed like the values were weird and unchanging until it warmed up. I think I was seeing 2.3V on Ox1 and around 300mV on Ox2. After a few minutes of idling, both began sweeping as expected.
 
Joined
Nov 11, 2014
Messages
159
Does it also work for diesel 80? The CEL never blink when I connect the paperclip between the TE1 and E1!
 
Joined
Feb 14, 2021
Messages
6
Location
victoria
His '94 is OBD1 and you can simply use the paperclip method to jumper terminals TE1 and E1 located on the black "Diagnostics" box on the passenger side under the hood. Turn the ignition to ON and read the blinks. There should be several posts that go into more detail on this but that's the quick version.

More information here: Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

:cheers:

--Mark
Is the 1993 a OB1
And would I be able to use the paper clip method
 

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