Jerry5300

2001 Astro. Driving at medium speed the brake and ABS lights come on and stay on, the speedo stops working and the trans won't shift. Pull over for 10 minutes and it resets just to do the samething in a few of miles. A couple of times the ABS motor activated at low speed for no apparent reason. The dealer said it was a shorted wire harness and they replaced it. 500 miles later the same thing. Dealer then said it was the speed sensor, they replaced it and said if thats not it is the computer? Several hundred miles later it continued to happen. I did not take it to the dealer again and took it to a couple of shops, no one found any codes etc. I have stocked and replaced several speed sensors. The last sensor I replaced lasted 5 miles before the samething happen. Unlike before even after sitting all night the brake light and ABS light and speedo are inoperable.

ihatemybike

I've been driving and wrenching these things for 14 years and you just stumped me. Any other problems? Has the van been damaged? Water, accident, etc?

Jerry5300

Thanks for responding. This vehicle has neve been damaged or wet. I started it when I got home from work....everything the same as it was with the addition of the ck engine light is on full time now. I will scan the code after work today.
It suspect the ABS brake module first or second the ECM.

djoker04

You can have the ECM Flashed!! Cheaper than replacing!! Check your relay for the ABS....you'll be surprised on the things that can loosen up or go out!

Jerry5300

I will check the relay and other connections at the next chance. Last night I recovered codes PO502 and 503 which says there is a problem with the (new) Speed sensor at the trans but I believe that could still be related to the ABS control module?

Is there any chance a wheel sensor could cause all of these symtoms?

Thumper_ehhhhh

Check your calapers. If one of them is ceased it will put both the abs and brake light on.

I had the same problem and was told it was my abs computer i laughed at the 2g they wanted. I changed both calapers as they were both starting to cease and that solved my problem. As for you speedo i have no clue.

msiverd

I have a 2000 chevy astro that is doing something very similar to your vehicle. The transmission goes into "safe mode" which will allow it only to have second and third gear. The check engine light will come on when it does this and usually takes about 10 minutes to act up after it has cooled off and has been reset. And when the check engine light comes on and the tranny messes up, the brake and abs lights come on as well. I just had the tranny rebuilt about 20,000 miles ago. I took the van back to the tranny shop and they replaced both shift selenoids, and retested the van several times. Each time the van put out a different code. First was 1-2 shift code, then 2-3 shift code, and then tcc code, which is the torque converter. So they then hooked a external box to the tranny to manually control the shifting in the transmission. When they did this it shifted perfect every single time. They then said it is an electrical problem somewhere else. I have since replaced the ignition switch, throttle position sensor, engine coolant temp sensor, and even the computer, but yet the problem persists. The only thing i am hearing now is that it must be a wiring harness problem. I found a bad wire on one of the plugs coming out of the computer and fixed it today. But i have to wait until Monday to get the codes cleared as mine stays on constantly now too. I think it may have blown thw 1-2 shift selenoid again. I will post more once i get the van back to the shop to see. If you find any more out with yours, please post as well as i am out of ideas. Thank you, Mike

jelectrico

My Friend. Connector to speed sensor has 2 wires ( third one is part bare part black and it is just a ground shield enclosed in a harness, but not connecting to sensor).
That connector and wiring to it is what you need to check in a first place, even before replacing a peed sensor.
Remove the connector ( look for the tab , then carefully raise the tab just enough to clear the notch on sensor.
Replace terminal if you find any dirt, oil or corrosion of terminals.
Are the wires ok? Can you check for continuity?
I had a broken wire right where the wire enters into the connector. Same problems, same codes.
After I replaced the connector everything is back to normal.
Here is what happens: If the ECBM does not receive a signal from speed sensor , it will not only turn the SES, Brake and ABS lights on, but it will also
prevent the the Transmission Clutch Control from shifting from 2 to 3 or 4, you will not have a speedometer and odometer reading, and high fuel consumption.
The connector is available from dealer at $ 55 .(GM part number 88987993)
or on internet for $30.( I cant rely on this aftermarket product , but its your choice).
New connector has same color wires- white.
Originally on the van you have Purple and Yellow? Make sure you mark with a marker the new wires before splicing, using the tab on the connector as a reference.
Good luck

jelectrico

Sensor itself, connector to sensor and ECBM.
You should get at least 4 code readings.
First must be P0502 ( VSS low output)
the rest of the codes will be connected to the first one.
Just check the connector for continuity of both wires, purple and yellow I suppose.
Be careful when connecting the new connector wires, as they are both white.
After circuit is operable If ECBM is ok, it will activate and speedometer and odometer will become operable immediately. ABS, Service engine soon , red Brake lights will be reset automatically.
Transmission will shift as it is supposed to.
ECBM may be repaired, if faulty.
I had an Identical problem on my 2000 Astro.
Now I am keeping a spare ABS, connector and Sensor , just in case.
Astro parts are becoming hard to find so who knows?
Since I love this van, I am intending to keep it for a long time.

jelectrico

I had exactly same problem , and fixed it myself.
Your VSS is installed in Transmission extension, on the side.
Check that connector plug on VSS . it may have a dirt or oil in it, or even broken wire. Mine was broken inside the insulation, and it was not visible.
Continuity test showed an open circuit,So I replaced the connector.
Just in case, here is the part number GM 88987993 , ACDelco PT1798.
Dealers price- mid $50s
internet price About $30