Korishan

My friend has a 99 Isuzu Rodeo 4x4. The ecu gets very hot after driving it for awhile. I have replaced the ECM with one from a local certified used parts place. He has informed me that he has sprayed WD-40 into the relay box under the hood because it was not running correctly and thought it was a relay problem. He soaked the replays. The motor would start sometimes when cold. Never when hot. The computer would give odd error codes. One was saying the EMC was an operating voltage error(if I remember correctly). So we replaced the ECM Now, when cold, it starts everytime. He's left it run idle for like 3 hours. He drives it a few blocks, and it dies. Let it cool down, and it cranks right up and he can drive it a little bit again. He has inofmrmed me that the ECM gets VERY hot (can fry an egg on it, he says). Any ideas?

rodeo4me

check ground connections as well as alternator.

Korishan

the old ecm wasn't getting hot. Nor was the relays. But with the replacement one, they do. I will have him check the voltage output of the alternator, though. Any other ideas to check on while we have the hood up?

Ramblin Fever

Do you still have the old ECM? If so, I'd be tempted to put it back in and go from there.

What were the codes?

__________________
1997 3.2L V6 Rodeo
32" Yoko's, 16x8 MB Wheels, 2" lift, Brushguard, KC Fog's, Loadwarrior Rack
On it's way to 185k strong

2004 3.4L Tacoma TRD off-road 4x4 Double cab
32" Yoko's, Westin Bull-bar, KC Fogs 60K miles

Korishan

One of the codes that it gave off was something about the ECM operating out of parameters. He lost the paper the codes were written on.
Also, the transmission light would come on, gas light, and several other engine codes.
I wish I could provide more information than this, I know it's vague.

Gizmo42

This makes me think the alternator is bad. Classic sign of a bad alternator on these vehicles is odd trouble lights. The orginal ecm might have been ok. If the alt is bad it could probably cause odd readings for the ecm.

Try turning on the fan for the heat/ac if it doesnt work then I would say definatly a bad alternator.

__________________
--Dave

1999 Rodeo LS 3.2 4x4 5 Speed
32x11.50-15 BFG T/A KO
3" Lift - Rancho 9000x
Rear No-Slip Locker
Flowmaster 2.25" 50 Series
There is a very fine line between "hobby" and "mental illness." - Dave Barry

amigo-2k

I vote for the alt too.

If the tranny light comes on with another light then it is typically the alt.

__________________
-Ryan
Isuzu Moderator

About the Owner
FAQ 98-04 Isuzu Rodeo, Rodeo Sport, Amigo, Trooper
2000 Amigo, V6, HT winter, ST summer, 2wd