1989 C1500, EGR, Headers Question

[evilunclegrimace]

So we have a little information but not really enough to be of any real help. For example, we know you have a new distributor, oil pressure sensor and coolant temp sensor. There are two of these, one for the gauge/light, one for the computer. Which did you replace?
How many miles on the engine? Does it have a stock TBI cam? Is the timing set properly at 0* BTDC? Look at the timing mark with the engine running at steady speeds, say, idle 1,500 and 2,500 RPM. Is the mark steady or jumping back and forth? What makes you think it is running lean?

There is only one SENDER in the left cylinder,it is for the gauge. there a sensor in the manifold that tell the ECM coolant temperature, it is a thermister and works oppisite of a sender( low temp high resistance-high temp low resistance)

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[FullBlowncustoms]

YES, all is correct. The temp sensor works fine. I changed the pressure sensor behind distributor. I think puter is bad. NO WAY to get any info off it... Advance working, but at times you give it throttle and advance retards before advancing.. No matter what, I should still get a connection with a jumper and I get nothing.. Is the ECM on 89 plug and play? or needs to be flashed like newer truck? I gotta look at it tomorrow, mouse damage maybe etc... IDK.... Any other type of relays under there near it? With key on it has a sound running like 20 secs, and if you start it up, then shut it off the same sounds runs like 20 secs near it again.. UNDER the dash. On 89 ECM if I pull it out, is there part number on them telling me if it is stock? or 89? and if they do modular changes on 89 ECM with performance ones is there a part number on it? letting me know if it is a stock one?
I read this on a 92, bit different but https://www.gmt400.com/threads/wont-go-into-diagnostic-mode.52538/

 

[FullBlowncustoms]

So I got under dash, remove the connector. And I see A and B terminals are pushed up. I pushed them down in, put jumper on and the BRAKE light flashes 9 times with a pause each time LOL... So something happened with ECM, a ground, or short from mice? When I stored it away I forgot and left the battery in it. was DEAD in summer when I got the truck out. IDK if that could drain out the ECM etc... EGR seems to not be working also. But some of the ECM must work or it would not fire up so fast starting it?

 

[Drunkcanuk]

So I got under dash, remove the connector. And I see A and B terminals are pushed up. I pushed them down in, put jumper on and the BRAKE light flashes 9 times with a pause each time LOL... So something happened with ECM, a ground, or short from mice? When I stored it away I forgot and left the battery in it. was DEAD in summer when I got the truck out. IDK if that could drain out the ECM etc... EGR seems to not be working also. But some of the ECM must work or it would not fire up so fast starting it?

Just a single flash 9 times?
Or was it a single flash, pause, 2 quick flashes, then repeats the cycle 3 times?

 

[Scooterwrench]

RWAB module is it's own circuit,has nothing to do with ECM. You may need to consult the service manual and see if someone has moved wires around in the ALDL connector.

 

[FullBlowncustoms]

Flashes 9 times over and over again, with a pause in between... Started it up later on and the flashes all came back with no jumper wire. Had to disconnect ground off battery so it would go away. Then I put jumper in again and it FIRST flashed 8 times, pause, then 9 flashes over and over constantly with pause in between.. Never 8 flashes again. Then had to disconnect battery ground again to make it go away if I start it up. all coming from brake light flashes LOL.... IDK if I can believe what I am seeing from brake light flashes on dash, and no code 12 connected LOL but code 89 I think? is ECM failure or something like that?

 

[Schurkey]

I'm thinking you're getting ONE long flash, then eight short flashes.

Look in the service manual for confirmation.

 

[FullBlowncustoms]

She lost her mind, all wigged out. Gets no flashes now from brake light on dash LOL... ECM behind the glovebox correct?

 

[Drunkcanuk]

She lost her mind, all wigged out. Gets no flashes now from brake light on dash LOL... ECM behind the glovebox correct?

Wow......not sure if you need a mechanic or a priest at this point!!!!! Lol
Ya.....it's behind the glovebox.
Good luck finding this gremlin!!!!

 

[Scooterwrench]

Check your wire positions at the ALDL and look to see if the terminals have gotten spread open by using to large a wire to jump with.

These are the position,use and wire colors from my 91 manual,yours should be the same.
ALDL socket,,,,,,,,,,,Use,,,,,,,,,,Wire Color

A,,,,,,,,ground,,,,,,,,,,Blk/wht
B,,,,,,,,self diagnostic input,,,,,,,,,Wht/blk
C,,,,,,,,A.I.R.,,,,,,,,,Brn
D,,,,,,,,Not Used
E,,,,,,,,Serial Data Man/700R4,160 Baud,,,,,,Orn/blk or Orn
F........TCC,,,,,,,,Tan/blk
G,,,,,,,Fuel Pump,,,,,,,,,Red
H.......RWAL Self Diagnostic(Brake Light),,,,,,,Wht
J........Not Used
K,,,,,,,Not Used
L,,,,,,,Not Used
M,,,,,,,Serial Data 4L80-E 8192 Baud......Orn/blk