I have a 88 chevy Cheyenne k1500 4.3L and it doesnt have 12 volts at dlc it is instead 1.8 volts but has the 12 volts at ecm fuse and all fuses.. My scan tool blinks quickly but wont start up. Just looking for ideas on my problem and how to tackle so thanks to helpers. I checked all fuses they were all good. I did notice that at the junction box under hood there is 3 orange wires spliced with a 4th wire connected to the junction box. If anyone with a 88 could post pics of how the orange wires are connected it would be very helpful.

 

GM OBD1 didn’t run battery power to the connector for the scan tools. You’ll have to use a DC adapter from the cigarette lighter socket or power it directly from the battery.

Is it not starting or not cranking?

 

thank you for your help and that information. It cranks over normally and it had spark and the fuel pump starts for 2 seconds then shuts off like normal just wont start. My truck doesn't have a cigarette lighter so would my best option be to splice that wire on back of dlc or run a hot wire from battery to the dlc b port and just plug adapter over it?

 

I don’t know what kind of scanner you have but the Tech 1 (GM tool) had 2 long lead wires on it so the tool could be plugged in at the connector and powered from the battery. If your scanner has a DC power port, you can get adapters to do the same. Check with the manufacturer to see what options are available.

I don’t recommend trying to add a power wire to the OBD port.

In the mean time, codes can be read by using a jumper wire (paper clip) between pins A&B, then turning the key on and counting the blinks of the check engine light.

 

I tried the paperclip method but all I keep getting is 12 over and over again. My scanner is a innova 3100rs and I called the company no luck it wont read obd1.

 

I was reading reviews and they said the innova 3123 is basically a expensive paper clip. Not sure what to buy but truck does have a check engine light on. The brake symbol also lit up with exclamation mark not sure if thats a sign of anything.

 

The code charts I read previously only started at code 13 but I did another search today and code 12 is infact a code if you also have a check engine light according to some. No reference pulses to ecm. It has a new pickup coil distributor and also new coil. so should I test icm before I try to test ecm? Thanks for your help

 

I believe 12 is normal, key on not running. Long blink is a 10, so, long blink with 2 short blinks is 12 ex.

 

Does the distributor have an icm ? You state new, I had an 82 with esc, had as it turned out bad insulation under the pickup coil to distributor, also the icm wasn't bad, but the parts store that sold it to me twice tested it, and as it turned out they destroyed it. I found that out 3rd time I took it back, had them test the module, then discovered they were plugging it in wrong.

 

Tonight I unplugged coolant temp plug and when I unplugged it the throttle body wire connector started making weird noises. I can try to post a video