1990 Toyota Pickup

Electrical problem
1990 Toyota Pickup 4 cyl Four Wheel Drive Manual

my truck kept popping EFI fuses so I check o2 sensor. When new engine was put in the mechanic never supported the wire going to the o2 sensor. Needless to say the exhaust melted the wire coating on all four wires to the o2. I have repaired the wires and so far no fuses have popped but the check engine light is still on. I unhooked the battery for 10 minutes and check engine light still on. The only thing I can thing that might be wrong in the carbon scoring in the wires from being in the exhaust. Maybe I didn't cut back far enough on the wire before reconnecting. Could this be it? A poor connection of the o2 wires?
Thank you,
July 17, 2010.

Find test connector near fuse box key on jumper wier from TE1 to E1. Check engine light will flash see diagram on how to read

Then post codes will advise. Wires to O2 neeed to soildered any increased resistence can cause trouble.
Thanks for donate

Jul 17, 2010.
Hi boxster617, Welcome to 2carpros and TY for the donation

Find the check connector Behind fuse/relay block No. 2. And jumper TE-1 to E-1 and read of the flashes and get back with the code/s we start here

Jul 17, 2010.
**_*___*****_* I think it is 21 then 51.
Does this sound right?

Jul 17, 2010.
Diagnostic Trouble Codes - 1990
11 ECU Power Supply.
12 Engine RPM Signal.
13 Engine RPM Signal.
14 Ignition Signal.
21 Oxygen Sensor (OS) Signal.
22 Water Temperature Sensor (THW) Signal.
24 Intake Air Temperature Sensor (THA) Signal.
25 Air/Fuel ratio lean.
26 Air/Fuel ratio rich.
27 Sub-oxygen sensor signal.
31 Air Flow Meter Signal.
32 Air Flow Meter Signal.
41 Throttle Position Sensor (TPS).
42 Vehicle Speed Sensor (VSS) Signal.
43 Starter Circuit Signal.
51 Switch Condition Signal.
71 EGR system malfunction.

Jul 17, 2010.
I think letting the vehicle sit for awhile is what it needed. I started it up about 2hrs later and no check engine light. I will keep monitoring the CEL but it looks like problem solved. Thank you for your knowledge. I have learned more problem solving skills.

Jul 18, 2010.
Four wire o2 sensors actually breathe through the plastic wire insulation, o2 sensors are very cheap and I recommend replacing it if you spliced wires. This sensor will adversely affect fuel economy and if it shorts out can kill the PCM. VERY expensive fix then! Once of prevention is worth.

Jul 29, 2010.