Chevy & GMC Vans

Still trying to figure problem with a "no start" purchase. Other post with UNGO alarm has been reversed engineer and pulled from vehicle. Took flying lessons of about 100 ft before it crashed and burned.

Can some one give a break down on the SES light when turning key to ON position? It appears to be the design through the brake light switch. Have no other light that comes up when turning key on, paper clip the ALDL block and all I'm getting is 7 flashes off brake light. Turn key on and 7 flashes from same light. This vehicle has been manipulated by others and virtually every piece of wire, circuit, relay etc has been checked, with some repairs and replacements. Ready to watch da flames real soon. LOL!!!

The following is from old posts:

To check for codes, jump A & B, then click they key ON. The SES light will blink all stored codes.

Jump A & H and the ABS light will blink stored trouble codes for that system.

Jump A & F and the TCC will lock in every gear except 1st. I have to caution you on this because it will lock the instant the trans is out of 1st. If you switch toa carb, all you gotta do is hook a switch up to this and flip it on when you're on the highway.

When you short the A - B connectors the SES (check engine light) will flash. You should see 1 flash, a short pause then 2 flashes (12). This one will always be there. Anything after 12 is a stored code. 13 would be 1 flash, short pause then 3 flashes (13). When it returns to 12 again you are done with reading the codes.

12-PCM/ECM is able to communicate
13-O2 sensor (open circuit)
14-ECT sensor circuit low (high temp indicated)
15-ECT sensor circuit high (low temp indicated)
16-VSS buffer fault
21-TP sensor circuit high (Signal voltage high)
22-TP sensor circuit low (signal voltage low)
23-IAT sensor circuit high (low temp indicated)
*24-VSS circuit low (transmission output speed signal)
25-IAT sensor circuit low (high temp indicated)
*28-Transmission Range Pressure switch assembly
32-EGR error
33-MAP sensor circuit high (low vacuum)
34-MAP sensor circuit low (high vacuum)
35-IAC error
*37-Brake switch stuck on
*38-Brake switch stuck off
42-Ignition control error
43-Knock sensor circuit
44-Lean exhaust
45-Rich exhaust
51-PROM (MEM.CAL) error
*52-System voltage high long
*53-System voltage high
54-Fuel pump relay circuit (low voltage)
55-Faulty PCM
*58-Transmission Fluid Temp sensor circuit low (high temp)
*59-Transmission Fluid Temp sensor circuit high (low temp)
*66-3-2 Control solenoid circuit fault
*67-TCC solenoid circuit fault
*69-TCC stuck "ON"
*72-VSS circuit loss (no signal)
*73-Pressure Control Solenoid fault
*75-System voltage low
*79-Transmission Fluid Overtemp
*81-2-3 Shift solenoid circuit fault
*82-1-2 Shift solenoid circuit fault

* indicates Transmission codes

Copy this to your clip board and print it out for future reference.

There are other specific codes that are not listed in the manuals that are vehicle specific.

The ABS codes are available as well.

Short pins A to H for the codes.

21- RF wheel sensor or open circuit
22- Missing RF speed signal
23- Erratic RF wheel signal
25- LF wheel sensor or open circuit
26- Missing LF speed signal
27- Erratic LF wheel signal
29- Simultaneous drop-out of front wheel signals
35- Open or grounded rear wheel signal circuit
36- Missing rear speed signal
37- Erratic rear speed signal
38- Wheel speed error
41-54- Control valves
65-66- Open or shorted pump motor relay
67- Open motor circuit or Shorted BPMV output
68- Locked motor or Shorted motor circuit
71-74- Memory errors
81- Brake switch circuit shorted or open
86- Shorted Antilock Indicator Lamp
88- Shorted Brake warning Lamp

Thanks for taking time to post the info dude, but it wasn't what I'm looking for by no means. Need to determine "How my SES light which I'm assuming is located on my Brake light displays when you turn the key on". Does it flash once, twice or seven times like mine is doing? My older 90 model has a Service Engine Soon light. This van has been butchered by few and my wits are at end troubleshooting this bugger.

All I can tell you is that your 95 van should be setup just like your old 90 van. They are both OBD1 vehicles with the same ALDL connecter and codes. You will have an SES (or an engine symbol, check engine), ABS, Airbag and Bake idiot lights come on with the key turned on. If your SES light is in your brake light you are saying, you are on your own as that is not where it should be and no one except who messed with the wiring will no why. In 95, as with any other year, you would turn the ignition on and the SES light will come on, no blinking, and stay on until the vehicle is started. It will then go off unless there is a stored code. If it is on then you would consult the above post for further diagnosis. Looks like you need to get a hold of the wiring schematics for your van and go at it. Sounds like fun right?

With the key cycled to "on", the SES light should come on and stay lit for a few seconds. It should not flash at all unless the van is running and there is a major issue.

lockdoc wrote:All I can tell you is that your 95 van should be setup just like your old 90 van. They are both OBD1 vehicles with the same ALDL connecter and codes. You will have an SES (or an engine symbol, check engine), ABS, Airbag and Bake idiot lights come on with the key turned on. If your SES light is in your brake light you are saying, you are on your own as that is not where it should be and no one except who messed with the wiring will no why. In 95, as with any other year, you would turn the ignition on and the SES light will come on, no blinking, and stay on until the vehicle is started. It will then go off unless there is a stored code. If it is on then you would consult the above post for further diagnosis. Looks like you need to get a hold of the wiring schematics for your van and go at it. Sounds like fun right?

Thanks Lockdoc for confirming the stupidity of my question. I was convinced that the 95 should have an ses light as the 90 model. So now that we have that straightened out the diagnose gets deeper. The piece of crap UNGO is gone,the brake light flashed in syncro when alarm loaded, pulled the unit out, thrown as far as it landed! But I need to figure out why and how some dumbass altered another wire of the ignition switch. Thnaks for the heads up lockdoc, surely on my own with this advanced troubleshooting. Will let you all know WTF do, should you have same issues one day. LOL!!!

Update on whats going on with this 95 Astro “NO Start” at purchase, that turned nightmare.
Since buying this van it has been an electrical nightmare. No SES light coming on making it impossible for finding a code, if there is any stored. Checked and replaced all bulbs within dash. Had an aftermarket security system that someone butchered into the harness, found manual for unit and my buddy did some reverse engineering to remove it from the harness. Narrowed down that possibility for “No Start”! Have spark with new cap, rotor, and wires, ignition Module, oddly the spark is yellowish.

First assumption was fuel pump it was only providing 8.5 volts at "gray" wire connection in wire harness when key turned on by a helper. We did have 65 psi initially when jumper wire to 12 volts in fuse block, but after continuous testing probably burnt the pump out, it was only putting out@ 35-40 psi at pressure gauge upon the next shot a troubleshooting. Checked wire harness from pump for continuity, all is fine. Checked and replaced Fuel Pump Relay. Went into tank pulled pump for the third time to check for breaks in wires to sending unit, all are like new. Replaced pump due to low pressure, including internal wires. Still have 8.5 volts on gray fuel pump wire and 35-40 psi when key turns On.

When buddy was troubleshooting fuse block to dash instrumentation wire harness he found AC/Heater circuit was a dead short. My recent discovery of a poorly repaired fusible link circuit showed evidence of a melted connector behind Battery below rear of fuse block. Hopefully this was caused by AC/heater circuit mentioned. Didn‘t take the time to follow the wires but the fuse link circuit diagram does include that circuit from one fuse link line being used.

So all this being mentioned and virtually every wire in obvious circuits that would cause a no start reviewed we decided to try the ECM from another wreck assuring the part numbers matched of course and nothing changed. Still have NO Start, low volts from new pump. All instrument bulbs lighting up “except the Service Engine Soon light”.
Heater blower, all headlights, tail and brake lights all work, but it just won’t start! Really took a gamble buying this van at an auction for $450 bucks but it has low miles at 205k, pretty sweet shape inside and out with every part on drive train visually looking tight. Reason for buying was they did drive it into the yard with discovering later a jumper wire from the fuel pump to the fuse block to get it running. Hmmmm?????? ](*,)

Is the ECM getting power? If the bulb is good, and it doesnt light up I'd check that or the bulb and power wiring.

Scott

sfeaver wrote:Is the ECM getting power? If the bulb is good, and it doesnt light up I'd check that or the bulb and power wiring.

Scott

Thanks Scott, been waiting for some extra time to check on things again. Bulb is newly replaced, power at wiring, just need to figure out how to test ECM for power. What actually grounds the ECM, shouldn't there be a black ground coming off ECM - body? Can't see how the plastic cross bracket could be ground. LOL, any tips greatly appreciated.

Ground (earth) is GREEN, not black. Black is usually a hot return.

CaptSquid wrote:Ground (earth) is GREEN, not black. Black is usually a hot return.

Well maybe the (earth) is green in some places dude but what I'm looking at in a PCM diagram is a black/white as system ground(2), perhaps tan off O2 sensor too. "Black Hot return", Hmmm are we confused with house wiring. LOL!

No ground wire on the PCM body. All grounds are through the wring harness itself for the ECM. And yes, all direct grounds are either solid black or black with a white stripe. There are other indirect grounds that are other colors but they all eventually splice into the black ones. Like the tan wire for the O2 sensor PCM ground.

lockdoc wrote:No ground wire on the PCM body. All grounds are through the wring harness itself for the ECM. And yes, all direct grounds are either solid black or black with a white stripe. There are other indirect grounds that are other colors but they all eventually splice into the black ones. Like the tan wire for the O2 sensor PCM ground.

Thanks Locdoc for clarifying my observations. One could be lead a stray if we believed everything we read. LOL

sfeaver wrote:Is the ECM getting power? If the bulb is good, and it doesnt light up I'd check that or the bulb and power wiring.

Scott

After taking a break from this nightmare I went at it once again earlier today. Was still stumped on why only power to one side of SES bulb, nothing coming back from PCM/ECM. Checking my oil pressure switch lead me to understand the fuel pump was running off the oil pump/switch @8.7V-9 with engine cranking, same volts on the fuel line(Gray). Okay now this was getting interesting, Went back to the ECM B fuse checked for power/volts from to Oil switch, maintained my 12V upto the harness connection entering the dog house plug socket for main engine harness. Went from there to orange 12V on PCM/ECM (Hot at all times), nothing???, went back to harness connection, struggled like a bugger to get my pudgy hands in there and try remove. After close to an hour got into the harness and needless to say my Orange 12V hot was dead short broken, with lots of corrosion covering it! Damn was I happy to find this! My defeat is over finally, my back is near crooked and perhaps another day I will solder that bugger leave the replacement ECM installed and start the F!$@^er. LOL!!!

Feels good to get it figured!! Congrats!!