E4OD Schematic

[iverger]

Anyone have a wiring diagram for an 89 with E4OD? My tach only works once the truck has warmed up for a while. It started after I pulled the cluster to fix the volt gauge. I pulled the cluster again and cleaned up the connections but that only made it worse, takes longer now. Could be coincidental though.

I've already replaced the tach sensor and traced the wires under the hood until they enter the harness.

Anyway, a schematic would be ideal.

Thanks,
Bob

 

[Black dawg]

check the relay

 

[iverger]

Which relay? Where would it be?

 

[tknomaj]

Ask and You Shall Receive

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Here You GO

 

[iverger]

Spectacular, Thanks. Now I have some work to do this weekend.

 

[iverger]

Update:

Used the schematic to trace all the way back to the cluster (shoulda started there ), oh well.

I pulled the tach from the cluster, fired up the truck and used the voltmeter to see what I had. There are 3 pins for the tach gauge: ground, 12 volts and one that varies with use of the throttle, seems logical. The variable one is dead at key off and on and about 10.75 volts at idle (on cold idle). Brapped the throttle and it jumps up to 11ish (probably 1000-1200 rpm).

So I take the tach itself (out of the truck), power it up and apply a full 12 volts to the variable pin. No action.

With all that said, the tach gauge appears to be the problem. But what's bothering me is that it seems like the tach is the end of the circuit and if the tach itself is dead how could that affect the TECA and put the tranny in limp mode. If there was a 4th pin sending a the regulated voltage back to the TECA it would make sense to me but the logic is escaping me on this one.

Guess I'll see if I can find a tach and see if it tests out deferent and go from there.

Bob

 

[pybyr]

This is great (the schematic)-- I got the shop manuals and engine manual for my 89 with E40D but haven't had any of the wiring diagrams. While we're asking, can anyone offer schematics for more of the rest of a 1989?

 

[pybyr]

by the way, what's the best/ easiest way to open and print these diagrams so that I can have them with me when working on the truck ?

 

[tknomaj]

1st problem the guage receives power and groun and the signal is in ac pulses and putting 12v dc to it will not make it read . so to test it properly connect it to signal gennerator . check for signal coming off tach sensor with a dvom in the a/c setting and start engine and rev it to see varying voltage rise with rpm and drop at idle . next go into cluster and check for duplication of signal at cluster connector. the dark green and yellow wire is the wire we are looking for signal on at tach sensor and at cluster. if no signal is received at sensor check black wire for ground no groun no signal generated. answer these questions and reply back the od light is on because the transmission control module is also not receiving a signal and does not know when to shift.

 

[tknomaj]

to answer the second do not print them out click on them and then click on them again and copy them to a flash drive save as a picture and then when you need them you have it and can print or use picture editing software to enlarge it and then print a realy big diagram . and when you need a diagram just pm me and i can post or email them to you

 

[iverger]

1st problem the guage receives power and groun and the signal is in ac pulses and putting 12v dc to it will not make it read . so to test it properly connect it to signal gennerator . check for signal coming off tach sensor with a dvom in the a/c setting and start engine and rev it to see varying voltage rise with rpm and drop at idle . next go into cluster and check for duplication of signal at cluster connector. the dark green and yellow wire is the wire we are looking for signal on at tach sensor and at cluster. if no signal is received at sensor check black wire for ground no groun no signal generated. answer these questions and reply back the od light is on because the transmission control module is also not receiving a signal and does not know when to shift.

crap, I stopped getting email updates on this thread for some reason. Not sure what a signal generator is supposed to look like, but I can get the sensor and cluster tests done tonight. As for the OD light, mine is off and is actually dead until the tach starts working again, then it operates normally.

Thanks,
Bob

 

[iverger]

.... check for signal coming off tach sensor with a dvom in the a/c setting and start engine and rev it to see varying voltage rise with rpm and drop at idle . next go into cluster and check for duplication of signal at cluster connector. the dark green and yellow wire is the wire we are looking for signal on at tach sensor and at cluster. if no signal is received at sensor check black wire for ground no groun no signal generated.....

OK, I officially must not know how to use a multimeter for AC I guess. It has a 500 and 200 setting on the V~. I set it on 200, attached the neg to ground and the pos to the green/yellow. That gave me a reading of 4.5 while the truck was running, cold and the tach was dead. I waited for it to warm up, the tach kicked in and it still read 4.5 and reving the engine didn't change it at all.

Since I'm not sure what I'm doing I attached the neg to the black/white wire (other side of the sensor) and had a reading of .3-.4 but the results were the same as above.

Suggestions?